├── .gitignore ├── LICENSE.md ├── Makefile ├── README.md ├── alpine-make-rootfs ├── boot_uefi_indirect.sh ├── bootloader.asm ├── buildroot_busybox.sh ├── buildroot_exec.sh ├── buildroot_mupdf.sh ├── busybox_config ├── chroot_init_root.sh ├── demo.gif ├── initramfs ├── base │ └── .gitkeep ├── bin │ ├── mount │ └── sh ├── dev │ └── .gitkeep ├── init ├── mnt │ └── .gitkeep ├── newroot │ └── .gitkeep ├── overlay │ └── .gitkeep ├── proc │ └── .gitkeep ├── sbin │ └── switch_root ├── setup_root ├── sys │ └── .gitkeep └── usr │ ├── bin │ └── yes │ └── sbin │ └── nologin ├── kernel_config ├── logo.png ├── logo.xcf ├── mk_buildroot.sh ├── mk_disk.py ├── mk_root.sh ├── mupdf-x11-minimal ├── APKBUILD ├── fix-big-endian.patch └── minimal.patch ├── rootfs_overlay └── etc │ ├── X11 │ └── xinit │ │ └── xinitrc.d │ │ └── 99-embedded-pdf │ ├── init.d │ ├── fix-apk-cache │ └── xorg │ ├── issue │ ├── motd │ └── xwelcome └── sample.pdf /.gitignore: -------------------------------------------------------------------------------- 1 | bootable.pdf 2 | unstreamed.pdf 3 | mupdf-x11-minimal.apk 4 | alpine_buildroot/ 5 | rootfs.sfs 6 | rootfs/ 7 | logo.ppm 8 | linux-* 9 | busybox-* 10 | initramfs/bin/busybox 11 | -------------------------------------------------------------------------------- /LICENSE.md: -------------------------------------------------------------------------------- 1 | ### GNU GENERAL PUBLIC LICENSE 2 | 3 | Version 3, 29 June 2007 4 | 5 | Copyright (C) 2007 Free Software Foundation, Inc. 6 | 7 | 8 | Everyone is permitted to copy and distribute verbatim copies of this 9 | license document, but changing it is not allowed. 10 | 11 | ### Preamble 12 | 13 | The GNU General Public License is a free, copyleft license for 14 | software and other kinds of works. 15 | 16 | The licenses for most software and other practical works are designed 17 | to take away your freedom to share and change the works. By contrast, 18 | the GNU General Public License is intended to guarantee your freedom 19 | to share and change all versions of a program--to make sure it remains 20 | free software for all its users. We, the Free Software Foundation, use 21 | the GNU General Public License for most of our software; it applies 22 | also to any other work released this way by its authors. You can apply 23 | it to your programs, too. 24 | 25 | When we speak of free software, we are referring to freedom, not 26 | price. Our General Public Licenses are designed to make sure that you 27 | have the freedom to distribute copies of free software (and charge for 28 | them if you wish), that you receive source code or can get it if you 29 | want it, that you can change the software or use pieces of it in new 30 | free programs, and that you know you can do these things. 31 | 32 | To protect your rights, we need to prevent others from denying you 33 | these rights or asking you to surrender the rights. Therefore, you 34 | have certain responsibilities if you distribute copies of the 35 | software, or if you modify it: responsibilities to respect the freedom 36 | of others. 37 | 38 | For example, if you distribute copies of such a program, whether 39 | gratis or for a fee, you must pass on to the recipients the same 40 | freedoms that you received. You must make sure that they, too, receive 41 | or can get the source code. And you must show them these terms so they 42 | know their rights. 43 | 44 | Developers that use the GNU GPL protect your rights with two steps: 45 | (1) assert copyright on the software, and (2) offer you this License 46 | giving you legal permission to copy, distribute and/or modify it. 47 | 48 | For the developers' and authors' protection, the GPL clearly explains 49 | that there is no warranty for this free software. For both users' and 50 | authors' sake, the GPL requires that modified versions be marked as 51 | changed, so that their problems will not be attributed erroneously to 52 | authors of previous versions. 53 | 54 | Some devices are designed to deny users access to install or run 55 | modified versions of the software inside them, although the 56 | manufacturer can do so. This is fundamentally incompatible with the 57 | aim of protecting users' freedom to change the software. The 58 | systematic pattern of such abuse occurs in the area of products for 59 | individuals to use, which is precisely where it is most unacceptable. 60 | Therefore, we have designed this version of the GPL to prohibit the 61 | practice for those products. If such problems arise substantially in 62 | other domains, we stand ready to extend this provision to those 63 | domains in future versions of the GPL, as needed to protect the 64 | freedom of users. 65 | 66 | Finally, every program is threatened constantly by software patents. 67 | States should not allow patents to restrict development and use of 68 | software on general-purpose computers, but in those that do, we wish 69 | to avoid the special danger that patents applied to a free program 70 | could make it effectively proprietary. To prevent this, the GPL 71 | assures that patents cannot be used to render the program non-free. 72 | 73 | The precise terms and conditions for copying, distribution and 74 | modification follow. 75 | 76 | ### TERMS AND CONDITIONS 77 | 78 | #### 0. Definitions. 79 | 80 | "This License" refers to version 3 of the GNU General Public License. 81 | 82 | "Copyright" also means copyright-like laws that apply to other kinds 83 | of works, such as semiconductor masks. 84 | 85 | "The Program" refers to any copyrightable work licensed under this 86 | License. Each licensee is addressed as "you". "Licensees" and 87 | "recipients" may be individuals or organizations. 88 | 89 | To "modify" a work means to copy from or adapt all or part of the work 90 | in a fashion requiring copyright permission, other than the making of 91 | an exact copy. The resulting work is called a "modified version" of 92 | the earlier work or a work "based on" the earlier work. 93 | 94 | A "covered work" means either the unmodified Program or a work based 95 | on the Program. 96 | 97 | To "propagate" a work means to do anything with it that, without 98 | permission, would make you directly or secondarily liable for 99 | infringement under applicable copyright law, except executing it on a 100 | computer or modifying a private copy. Propagation includes copying, 101 | distribution (with or without modification), making available to the 102 | public, and in some countries other activities as well. 103 | 104 | To "convey" a work means any kind of propagation that enables other 105 | parties to make or receive copies. Mere interaction with a user 106 | through a computer network, with no transfer of a copy, is not 107 | conveying. 108 | 109 | An interactive user interface displays "Appropriate Legal Notices" to 110 | the extent that it includes a convenient and prominently visible 111 | feature that (1) displays an appropriate copyright notice, and (2) 112 | tells the user that there is no warranty for the work (except to the 113 | extent that warranties are provided), that licensees may convey the 114 | work under this License, and how to view a copy of this License. If 115 | the interface presents a list of user commands or options, such as a 116 | menu, a prominent item in the list meets this criterion. 117 | 118 | #### 1. Source Code. 119 | 120 | The "source code" for a work means the preferred form of the work for 121 | making modifications to it. "Object code" means any non-source form of 122 | a work. 123 | 124 | A "Standard Interface" means an interface that either is an official 125 | standard defined by a recognized standards body, or, in the case of 126 | interfaces specified for a particular programming language, one that 127 | is widely used among developers working in that language. 128 | 129 | The "System Libraries" of an executable work include anything, other 130 | than the work as a whole, that (a) is included in the normal form of 131 | packaging a Major Component, but which is not part of that Major 132 | Component, and (b) serves only to enable use of the work with that 133 | Major Component, or to implement a Standard Interface for which an 134 | implementation is available to the public in source code form. A 135 | "Major Component", in this context, means a major essential component 136 | (kernel, window system, and so on) of the specific operating system 137 | (if any) on which the executable work runs, or a compiler used to 138 | produce the work, or an object code interpreter used to run it. 139 | 140 | The "Corresponding Source" for a work in object code form means all 141 | the source code needed to generate, install, and (for an executable 142 | work) run the object code and to modify the work, including scripts to 143 | control those activities. However, it does not include the work's 144 | System Libraries, or general-purpose tools or generally available free 145 | programs which are used unmodified in performing those activities but 146 | which are not part of the work. For example, Corresponding Source 147 | includes interface definition files associated with source files for 148 | the work, and the source code for shared libraries and dynamically 149 | linked subprograms that the work is specifically designed to require, 150 | such as by intimate data communication or control flow between those 151 | subprograms and other parts of the work. 152 | 153 | The Corresponding Source need not include anything that users can 154 | regenerate automatically from other parts of the Corresponding Source. 155 | 156 | The Corresponding Source for a work in source code form is that same 157 | work. 158 | 159 | #### 2. Basic Permissions. 160 | 161 | All rights granted under this License are granted for the term of 162 | copyright on the Program, and are irrevocable provided the stated 163 | conditions are met. This License explicitly affirms your unlimited 164 | permission to run the unmodified Program. The output from running a 165 | covered work is covered by this License only if the output, given its 166 | content, constitutes a covered work. This License acknowledges your 167 | rights of fair use or other equivalent, as provided by copyright law. 168 | 169 | You may make, run and propagate covered works that you do not convey, 170 | without conditions so long as your license otherwise remains in force. 171 | You may convey covered works to others for the sole purpose of having 172 | them make modifications exclusively for you, or provide you with 173 | facilities for running those works, provided that you comply with the 174 | terms of this License in conveying all material for which you do not 175 | control copyright. Those thus making or running the covered works for 176 | you must do so exclusively on your behalf, under your direction and 177 | control, on terms that prohibit them from making any copies of your 178 | copyrighted material outside their relationship with you. 179 | 180 | Conveying under any other circumstances is permitted solely under the 181 | conditions stated below. Sublicensing is not allowed; section 10 makes 182 | it unnecessary. 183 | 184 | #### 3. Protecting Users' Legal Rights From Anti-Circumvention Law. 185 | 186 | No covered work shall be deemed part of an effective technological 187 | measure under any applicable law fulfilling obligations under article 188 | 11 of the WIPO copyright treaty adopted on 20 December 1996, or 189 | similar laws prohibiting or restricting circumvention of such 190 | measures. 191 | 192 | When you convey a covered work, you waive any legal power to forbid 193 | circumvention of technological measures to the extent such 194 | circumvention is effected by exercising rights under this License with 195 | respect to the covered work, and you disclaim any intention to limit 196 | operation or modification of the work as a means of enforcing, against 197 | the work's users, your or third parties' legal rights to forbid 198 | circumvention of technological measures. 199 | 200 | #### 4. Conveying Verbatim Copies. 201 | 202 | You may convey verbatim copies of the Program's source code as you 203 | receive it, in any medium, provided that you conspicuously and 204 | appropriately publish on each copy an appropriate copyright notice; 205 | keep intact all notices stating that this License and any 206 | non-permissive terms added in accord with section 7 apply to the code; 207 | keep intact all notices of the absence of any warranty; and give all 208 | recipients a copy of this License along with the Program. 209 | 210 | You may charge any price or no price for each copy that you convey, 211 | and you may offer support or warranty protection for a fee. 212 | 213 | #### 5. Conveying Modified Source Versions. 214 | 215 | You may convey a work based on the Program, or the modifications to 216 | produce it from the Program, in the form of source code under the 217 | terms of section 4, provided that you also meet all of these 218 | conditions: 219 | 220 | - a) The work must carry prominent notices stating that you modified 221 | it, and giving a relevant date. 222 | - b) The work must carry prominent notices stating that it is 223 | released under this License and any conditions added under 224 | section 7. This requirement modifies the requirement in section 4 225 | to "keep intact all notices". 226 | - c) You must license the entire work, as a whole, under this 227 | License to anyone who comes into possession of a copy. This 228 | License will therefore apply, along with any applicable section 7 229 | additional terms, to the whole of the work, and all its parts, 230 | regardless of how they are packaged. This License gives no 231 | permission to license the work in any other way, but it does not 232 | invalidate such permission if you have separately received it. 233 | - d) If the work has interactive user interfaces, each must display 234 | Appropriate Legal Notices; however, if the Program has interactive 235 | interfaces that do not display Appropriate Legal Notices, your 236 | work need not make them do so. 237 | 238 | A compilation of a covered work with other separate and independent 239 | works, which are not by their nature extensions of the covered work, 240 | and which are not combined with it such as to form a larger program, 241 | in or on a volume of a storage or distribution medium, is called an 242 | "aggregate" if the compilation and its resulting copyright are not 243 | used to limit the access or legal rights of the compilation's users 244 | beyond what the individual works permit. Inclusion of a covered work 245 | in an aggregate does not cause this License to apply to the other 246 | parts of the aggregate. 247 | 248 | #### 6. Conveying Non-Source Forms. 249 | 250 | You may convey a covered work in object code form under the terms of 251 | sections 4 and 5, provided that you also convey the machine-readable 252 | Corresponding Source under the terms of this License, in one of these 253 | ways: 254 | 255 | - a) Convey the object code in, or embodied in, a physical product 256 | (including a physical distribution medium), accompanied by the 257 | Corresponding Source fixed on a durable physical medium 258 | customarily used for software interchange. 259 | - b) Convey the object code in, or embodied in, a physical product 260 | (including a physical distribution medium), accompanied by a 261 | written offer, valid for at least three years and valid for as 262 | long as you offer spare parts or customer support for that product 263 | model, to give anyone who possesses the object code either (1) a 264 | copy of the Corresponding Source for all the software in the 265 | product that is covered by this License, on a durable physical 266 | medium customarily used for software interchange, for a price no 267 | more than your reasonable cost of physically performing this 268 | conveying of source, or (2) access to copy the Corresponding 269 | Source from a network server at no charge. 270 | - c) Convey individual copies of the object code with a copy of the 271 | written offer to provide the Corresponding Source. This 272 | alternative is allowed only occasionally and noncommercially, and 273 | only if you received the object code with such an offer, in accord 274 | with subsection 6b. 275 | - d) Convey the object code by offering access from a designated 276 | place (gratis or for a charge), and offer equivalent access to the 277 | Corresponding Source in the same way through the same place at no 278 | further charge. You need not require recipients to copy the 279 | Corresponding Source along with the object code. If the place to 280 | copy the object code is a network server, the Corresponding Source 281 | may be on a different server (operated by you or a third party) 282 | that supports equivalent copying facilities, provided you maintain 283 | clear directions next to the object code saying where to find the 284 | Corresponding Source. Regardless of what server hosts the 285 | Corresponding Source, you remain obligated to ensure that it is 286 | available for as long as needed to satisfy these requirements. 287 | - e) Convey the object code using peer-to-peer transmission, 288 | provided you inform other peers where the object code and 289 | Corresponding Source of the work are being offered to the general 290 | public at no charge under subsection 6d. 291 | 292 | A separable portion of the object code, whose source code is excluded 293 | from the Corresponding Source as a System Library, need not be 294 | included in conveying the object code work. 295 | 296 | A "User Product" is either (1) a "consumer product", which means any 297 | tangible personal property which is normally used for personal, 298 | family, or household purposes, or (2) anything designed or sold for 299 | incorporation into a dwelling. In determining whether a product is a 300 | consumer product, doubtful cases shall be resolved in favor of 301 | coverage. For a particular product received by a particular user, 302 | "normally used" refers to a typical or common use of that class of 303 | product, regardless of the status of the particular user or of the way 304 | in which the particular user actually uses, or expects or is expected 305 | to use, the product. A product is a consumer product regardless of 306 | whether the product has substantial commercial, industrial or 307 | non-consumer uses, unless such uses represent the only significant 308 | mode of use of the product. 309 | 310 | "Installation Information" for a User Product means any methods, 311 | procedures, authorization keys, or other information required to 312 | install and execute modified versions of a covered work in that User 313 | Product from a modified version of its Corresponding Source. The 314 | information must suffice to ensure that the continued functioning of 315 | the modified object code is in no case prevented or interfered with 316 | solely because modification has been made. 317 | 318 | If you convey an object code work under this section in, or with, or 319 | specifically for use in, a User Product, and the conveying occurs as 320 | part of a transaction in which the right of possession and use of the 321 | User Product is transferred to the recipient in perpetuity or for a 322 | fixed term (regardless of how the transaction is characterized), the 323 | Corresponding Source conveyed under this section must be accompanied 324 | by the Installation Information. But this requirement does not apply 325 | if neither you nor any third party retains the ability to install 326 | modified object code on the User Product (for example, the work has 327 | been installed in ROM). 328 | 329 | The requirement to provide Installation Information does not include a 330 | requirement to continue to provide support service, warranty, or 331 | updates for a work that has been modified or installed by the 332 | recipient, or for the User Product in which it has been modified or 333 | installed. Access to a network may be denied when the modification 334 | itself materially and adversely affects the operation of the network 335 | or violates the rules and protocols for communication across the 336 | network. 337 | 338 | Corresponding Source conveyed, and Installation Information provided, 339 | in accord with this section must be in a format that is publicly 340 | documented (and with an implementation available to the public in 341 | source code form), and must require no special password or key for 342 | unpacking, reading or copying. 343 | 344 | #### 7. Additional Terms. 345 | 346 | "Additional permissions" are terms that supplement the terms of this 347 | License by making exceptions from one or more of its conditions. 348 | Additional permissions that are applicable to the entire Program shall 349 | be treated as though they were included in this License, to the extent 350 | that they are valid under applicable law. If additional permissions 351 | apply only to part of the Program, that part may be used separately 352 | under those permissions, but the entire Program remains governed by 353 | this License without regard to the additional permissions. 354 | 355 | When you convey a copy of a covered work, you may at your option 356 | remove any additional permissions from that copy, or from any part of 357 | it. (Additional permissions may be written to require their own 358 | removal in certain cases when you modify the work.) You may place 359 | additional permissions on material, added by you to a covered work, 360 | for which you have or can give appropriate copyright permission. 361 | 362 | Notwithstanding any other provision of this License, for material you 363 | add to a covered work, you may (if authorized by the copyright holders 364 | of that material) supplement the terms of this License with terms: 365 | 366 | - a) Disclaiming warranty or limiting liability differently from the 367 | terms of sections 15 and 16 of this License; or 368 | - b) Requiring preservation of specified reasonable legal notices or 369 | author attributions in that material or in the Appropriate Legal 370 | Notices displayed by works containing it; or 371 | - c) Prohibiting misrepresentation of the origin of that material, 372 | or requiring that modified versions of such material be marked in 373 | reasonable ways as different from the original version; or 374 | - d) Limiting the use for publicity purposes of names of licensors 375 | or authors of the material; or 376 | - e) Declining to grant rights under trademark law for use of some 377 | trade names, trademarks, or service marks; or 378 | - f) Requiring indemnification of licensors and authors of that 379 | material by anyone who conveys the material (or modified versions 380 | of it) with contractual assumptions of liability to the recipient, 381 | for any liability that these contractual assumptions directly 382 | impose on those licensors and authors. 383 | 384 | All other non-permissive additional terms are considered "further 385 | restrictions" within the meaning of section 10. If the Program as you 386 | received it, or any part of it, contains a notice stating that it is 387 | governed by this License along with a term that is a further 388 | restriction, you may remove that term. If a license document contains 389 | a further restriction but permits relicensing or conveying under this 390 | License, you may add to a covered work material governed by the terms 391 | of that license document, provided that the further restriction does 392 | not survive such relicensing or conveying. 393 | 394 | If you add terms to a covered work in accord with this section, you 395 | must place, in the relevant source files, a statement of the 396 | additional terms that apply to those files, or a notice indicating 397 | where to find the applicable terms. 398 | 399 | Additional terms, permissive or non-permissive, may be stated in the 400 | form of a separately written license, or stated as exceptions; the 401 | above requirements apply either way. 402 | 403 | #### 8. Termination. 404 | 405 | You may not propagate or modify a covered work except as expressly 406 | provided under this License. Any attempt otherwise to propagate or 407 | modify it is void, and will automatically terminate your rights under 408 | this License (including any patent licenses granted under the third 409 | paragraph of section 11). 410 | 411 | However, if you cease all violation of this License, then your license 412 | from a particular copyright holder is reinstated (a) provisionally, 413 | unless and until the copyright holder explicitly and finally 414 | terminates your license, and (b) permanently, if the copyright holder 415 | fails to notify you of the violation by some reasonable means prior to 416 | 60 days after the cessation. 417 | 418 | Moreover, your license from a particular copyright holder is 419 | reinstated permanently if the copyright holder notifies you of the 420 | violation by some reasonable means, this is the first time you have 421 | received notice of violation of this License (for any work) from that 422 | copyright holder, and you cure the violation prior to 30 days after 423 | your receipt of the notice. 424 | 425 | Termination of your rights under this section does not terminate the 426 | licenses of parties who have received copies or rights from you under 427 | this License. If your rights have been terminated and not permanently 428 | reinstated, you do not qualify to receive new licenses for the same 429 | material under section 10. 430 | 431 | #### 9. Acceptance Not Required for Having Copies. 432 | 433 | You are not required to accept this License in order to receive or run 434 | a copy of the Program. Ancillary propagation of a covered work 435 | occurring solely as a consequence of using peer-to-peer transmission 436 | to receive a copy likewise does not require acceptance. However, 437 | nothing other than this License grants you permission to propagate or 438 | modify any covered work. These actions infringe copyright if you do 439 | not accept this License. Therefore, by modifying or propagating a 440 | covered work, you indicate your acceptance of this License to do so. 441 | 442 | #### 10. Automatic Licensing of Downstream Recipients. 443 | 444 | Each time you convey a covered work, the recipient automatically 445 | receives a license from the original licensors, to run, modify and 446 | propagate that work, subject to this License. You are not responsible 447 | for enforcing compliance by third parties with this License. 448 | 449 | An "entity transaction" is a transaction transferring control of an 450 | organization, or substantially all assets of one, or subdividing an 451 | organization, or merging organizations. If propagation of a covered 452 | work results from an entity transaction, each party to that 453 | transaction who receives a copy of the work also receives whatever 454 | licenses to the work the party's predecessor in interest had or could 455 | give under the previous paragraph, plus a right to possession of the 456 | Corresponding Source of the work from the predecessor in interest, if 457 | the predecessor has it or can get it with reasonable efforts. 458 | 459 | You may not impose any further restrictions on the exercise of the 460 | rights granted or affirmed under this License. For example, you may 461 | not impose a license fee, royalty, or other charge for exercise of 462 | rights granted under this License, and you may not initiate litigation 463 | (including a cross-claim or counterclaim in a lawsuit) alleging that 464 | any patent claim is infringed by making, using, selling, offering for 465 | sale, or importing the Program or any portion of it. 466 | 467 | #### 11. Patents. 468 | 469 | A "contributor" is a copyright holder who authorizes use under this 470 | License of the Program or a work on which the Program is based. The 471 | work thus licensed is called the contributor's "contributor version". 472 | 473 | A contributor's "essential patent claims" are all patent claims owned 474 | or controlled by the contributor, whether already acquired or 475 | hereafter acquired, that would be infringed by some manner, permitted 476 | by this License, of making, using, or selling its contributor version, 477 | but do not include claims that would be infringed only as a 478 | consequence of further modification of the contributor version. For 479 | purposes of this definition, "control" includes the right to grant 480 | patent sublicenses in a manner consistent with the requirements of 481 | this License. 482 | 483 | Each contributor grants you a non-exclusive, worldwide, royalty-free 484 | patent license under the contributor's essential patent claims, to 485 | make, use, sell, offer for sale, import and otherwise run, modify and 486 | propagate the contents of its contributor version. 487 | 488 | In the following three paragraphs, a "patent license" is any express 489 | agreement or commitment, however denominated, not to enforce a patent 490 | (such as an express permission to practice a patent or covenant not to 491 | sue for patent infringement). To "grant" such a patent license to a 492 | party means to make such an agreement or commitment not to enforce a 493 | patent against the party. 494 | 495 | If you convey a covered work, knowingly relying on a patent license, 496 | and the Corresponding Source of the work is not available for anyone 497 | to copy, free of charge and under the terms of this License, through a 498 | publicly available network server or other readily accessible means, 499 | then you must either (1) cause the Corresponding Source to be so 500 | available, or (2) arrange to deprive yourself of the benefit of the 501 | patent license for this particular work, or (3) arrange, in a manner 502 | consistent with the requirements of this License, to extend the patent 503 | license to downstream recipients. "Knowingly relying" means you have 504 | actual knowledge that, but for the patent license, your conveying the 505 | covered work in a country, or your recipient's use of the covered work 506 | in a country, would infringe one or more identifiable patents in that 507 | country that you have reason to believe are valid. 508 | 509 | If, pursuant to or in connection with a single transaction or 510 | arrangement, you convey, or propagate by procuring conveyance of, a 511 | covered work, and grant a patent license to some of the parties 512 | receiving the covered work authorizing them to use, propagate, modify 513 | or convey a specific copy of the covered work, then the patent license 514 | you grant is automatically extended to all recipients of the covered 515 | work and works based on it. 516 | 517 | A patent license is "discriminatory" if it does not include within the 518 | scope of its coverage, prohibits the exercise of, or is conditioned on 519 | the non-exercise of one or more of the rights that are specifically 520 | granted under this License. You may not convey a covered work if you 521 | are a party to an arrangement with a third party that is in the 522 | business of distributing software, under which you make payment to the 523 | third party based on the extent of your activity of conveying the 524 | work, and under which the third party grants, to any of the parties 525 | who would receive the covered work from you, a discriminatory patent 526 | license (a) in connection with copies of the covered work conveyed by 527 | you (or copies made from those copies), or (b) primarily for and in 528 | connection with specific products or compilations that contain the 529 | covered work, unless you entered into that arrangement, or that patent 530 | license was granted, prior to 28 March 2007. 531 | 532 | Nothing in this License shall be construed as excluding or limiting 533 | any implied license or other defenses to infringement that may 534 | otherwise be available to you under applicable patent law. 535 | 536 | #### 12. No Surrender of Others' Freedom. 537 | 538 | If conditions are imposed on you (whether by court order, agreement or 539 | otherwise) that contradict the conditions of this License, they do not 540 | excuse you from the conditions of this License. If you cannot convey a 541 | covered work so as to satisfy simultaneously your obligations under 542 | this License and any other pertinent obligations, then as a 543 | consequence you may not convey it at all. For example, if you agree to 544 | terms that obligate you to collect a royalty for further conveying 545 | from those to whom you convey the Program, the only way you could 546 | satisfy both those terms and this License would be to refrain entirely 547 | from conveying the Program. 548 | 549 | #### 13. Use with the GNU Affero General Public License. 550 | 551 | Notwithstanding any other provision of this License, you have 552 | permission to link or combine any covered work with a work licensed 553 | under version 3 of the GNU Affero General Public License into a single 554 | combined work, and to convey the resulting work. The terms of this 555 | License will continue to apply to the part which is the covered work, 556 | but the special requirements of the GNU Affero General Public License, 557 | section 13, concerning interaction through a network will apply to the 558 | combination as such. 559 | 560 | #### 14. Revised Versions of this License. 561 | 562 | The Free Software Foundation may publish revised and/or new versions 563 | of the GNU General Public License from time to time. Such new versions 564 | will be similar in spirit to the present version, but may differ in 565 | detail to address new problems or concerns. 566 | 567 | Each version is given a distinguishing version number. If the Program 568 | specifies that a certain numbered version of the GNU General Public 569 | License "or any later version" applies to it, you have the option of 570 | following the terms and conditions either of that numbered version or 571 | of any later version published by the Free Software Foundation. If the 572 | Program does not specify a version number of the GNU General Public 573 | License, you may choose any version ever published by the Free 574 | Software Foundation. 575 | 576 | If the Program specifies that a proxy can decide which future versions 577 | of the GNU General Public License can be used, that proxy's public 578 | statement of acceptance of a version permanently authorizes you to 579 | choose that version for the Program. 580 | 581 | Later license versions may give you additional or different 582 | permissions. However, no additional obligations are imposed on any 583 | author or copyright holder as a result of your choosing to follow a 584 | later version. 585 | 586 | #### 15. Disclaimer of Warranty. 587 | 588 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 589 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 590 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT 591 | WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT 592 | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 593 | A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND 594 | PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE 595 | DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR 596 | CORRECTION. 597 | 598 | #### 16. Limitation of Liability. 599 | 600 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 601 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR 602 | CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, 603 | INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES 604 | ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT 605 | NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR 606 | LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM 607 | TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER 608 | PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 609 | 610 | #### 17. Interpretation of Sections 15 and 16. 611 | 612 | If the disclaimer of warranty and limitation of liability provided 613 | above cannot be given local legal effect according to their terms, 614 | reviewing courts shall apply local law that most closely approximates 615 | an absolute waiver of all civil liability in connection with the 616 | Program, unless a warranty or assumption of liability accompanies a 617 | copy of the Program in return for a fee. 618 | 619 | END OF TERMS AND CONDITIONS 620 | 621 | ### How to Apply These Terms to Your New Programs 622 | 623 | If you develop a new program, and you want it to be of the greatest 624 | possible use to the public, the best way to achieve this is to make it 625 | free software which everyone can redistribute and change under these 626 | terms. 627 | 628 | To do so, attach the following notices to the program. It is safest to 629 | attach them to the start of each source file to most effectively state 630 | the exclusion of warranty; and each file should have at least the 631 | "copyright" line and a pointer to where the full notice is found. 632 | 633 | 634 | Copyright (C) 635 | 636 | This program is free software: you can redistribute it and/or modify 637 | it under the terms of the GNU General Public License as published by 638 | the Free Software Foundation, either version 3 of the License, or 639 | (at your option) any later version. 640 | 641 | This program is distributed in the hope that it will be useful, 642 | but WITHOUT ANY WARRANTY; without even the implied warranty of 643 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 644 | GNU General Public License for more details. 645 | 646 | You should have received a copy of the GNU General Public License 647 | along with this program. If not, see . 648 | 649 | Also add information on how to contact you by electronic and paper 650 | mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands \`show w' and \`show c' should show the 661 | appropriate parts of the General Public License. Of course, your 662 | program's commands might be different; for a GUI interface, you would 663 | use an "about box". 664 | 665 | You should also get your employer (if you work as a programmer) or 666 | school, if any, to sign a "copyright disclaimer" for the program, if 667 | necessary. For more information on this, and how to apply and follow 668 | the GNU GPL, see . 669 | 670 | The GNU General Public License does not permit incorporating your 671 | program into proprietary programs. If your program is a subroutine 672 | library, you may consider it more useful to permit linking proprietary 673 | applications with the library. If this is what you want to do, use the 674 | GNU Lesser General Public License instead of this License. But first, 675 | please read . 676 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | BUSYBOX_VERSION=1.31.1 2 | LINUX_VERSION=5.4.36 3 | 4 | BUSYBOX_DIR=busybox-$(BUSYBOX_VERSION) 5 | LINUX_DIR=linux-$(LINUX_VERSION) 6 | 7 | BUSYBOX_BIN=$(BUSYBOX_DIR)/busybox 8 | KERNEL_IMAGE=$(LINUX_DIR)/arch/x86_64/boot/bzImage 9 | 10 | PDF := sample.pdf 11 | 12 | JOBS=$(shell nproc) 13 | DIST := bootable.pdf 14 | 15 | MKSQUASH_OPTS := -b 1M -comp xz -Xdict-size 100% 16 | QEMU_CMD := qemu-system-x86_64 -machine q35 -m 2G -cpu host -smp 2 -enable-kvm -vga qxl -usb -device usb-tablet -net nic -net user 17 | OVMF := /usr/share/edk2-ovmf/x64/OVMF_CODE.fd 18 | 19 | .PHONY: default all clean app boot_bios boot_uefi boot_uefi_indirect 20 | 21 | default: $(DIST) 22 | all: default 23 | 24 | $(BUSYBOX_DIR).tar.bz2: 25 | curl -L -o $@ https://busybox.net/downloads/$@ 26 | $(BUSYBOX_DIR): $(BUSYBOX_DIR).tar.bz2 27 | tar jxf $< 28 | cp busybox_config $@/.config 29 | 30 | $(LINUX_DIR).tar.xz: 31 | curl -L -o $@ https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/$@ 32 | $(LINUX_DIR): $(LINUX_DIR).tar.xz 33 | tar Jxf $< 34 | INITRAMFS_UID=$$(id -u) INITRAMFS_GID=$$(id -g) envsubst < kernel_config > $@/.config 35 | 36 | alpine_buildroot/: 37 | ./mk_buildroot.sh $@ 38 | 39 | $(BUSYBOX_BIN): | $(BUSYBOX_DIR) $(BUSYBOX_DIR)/.config alpine_buildroot/ 40 | ./buildroot_exec.sh alpine_buildroot/ ./buildroot_busybox.sh $(BUSYBOX_DIR) -j$(JOBS) 41 | initramfs/bin/busybox: $(BUSYBOX_BIN) 42 | cp $< $@ 43 | 44 | logo.ppm: logo.png 45 | pngtopnm $< | pamscale -width 80 -height 80 | ppmquant -fs 224 | pnmtoplainpnm > $@ 46 | $(KERNEL_IMAGE): $(LINUX_DIR) $(LINUX_DIR)/.config logo.ppm initramfs/ initramfs/bin/busybox 47 | cp logo.ppm $ CVos - a bootable PDF 2 | CVos "converts" a PDF into a bootable disk image (based on Linux) which can view 3 | itself - while remaining usable as a PDF! 4 | 5 |

6 | Demo 7 |

8 | 9 | You can grab a sample bootable PDF from the [releases page](https://github.com/devplayer0/cvos/releases) (it's a 10 | copy of my CV!). 11 | 12 | Inspired by [Curriculum Bootloader](https://github.com/pjimenezmateo/curriculum-bootloader). 13 | 14 | ## How do I boot it? 15 | Glad you asked. There are two ways to boot a CVos PDF: 16 | - Write the PDF directly to a disk (e.g. flash drive) - bootable by BIOS / UEFI systems 17 | - Execute the PDF as an EFI binary 18 | 19 | ### In a virtual machine 20 | The easiest way to try a CVos PDF. 21 | You should be able to attach the PDF as a disk image to the VM and boot. 22 | 23 | If you're on Linux and have [QEMU][qemu] installed, you can use the `Makefile` in this repo: 24 | - `make DIST=/path/to/bootable.pdf boot_bios` will boot the PDF with a BIOS-based VM 25 | - `make DIST=/path/to/bootable.pdf boot_uefi` will use a UEFI-based VM (requires [OVMF][ovmf]) 26 | - `make DIST=/path/to/bootable.pdf boot_uefi_indirect` will create a temporary disk image and copy the PDF to it, 27 | executing the PDF as an EFI binary (also requires [OVMF][ovmf]) 28 | 29 | See `QEMU_CMD` for the base command used to run QEMU. 30 | Pass `OVMF=/path/to/OVMF_CODE.fd` to `make` if your OVMF BIOS file isn't in the default location. 31 | 32 | ### On real hardware 33 | An x86_64-based system is required. 34 | 35 | By writing the PDF directly to a disk, you can boot it on a BIOS / UEFI system: 36 | 1. Run `dd if=/path/to/bootable.pdf of=/dev/SOMETHING bs=1M oflag=direct` 37 | - **Be sure to replace `/dev/SOMETHING` with the path to your USB drive** 38 | 2. Start your machine and boot from the drive (you will probably need to spam a key to get a boot menu) 39 | 40 | If you're on Windows, something like [Rufus](https://rufus.ie) in DD mode should work. 41 | 42 | You can also copy the PDF to a FAT12/16/32-formatted disk and boot as an EFI binary (requires a UEFI system): 43 | 1. Create the directories `/EFI/Boot` in the root of the drive 44 | 2. Copy your PDF to `/EFI/Boot/bootx64.efi` (note the changed extension) 45 | 3. Boot your machine from the disk as before 46 | 47 | ## How can I make my own PDF bootable? 48 | You'll need: 49 | - A Linux system 50 | - Git 51 | - The dependencies needed to build the Linux kernel 52 | - curl 53 | - [Netpbm](http://netpbm.sourceforge.net) 54 | - sudo 55 | - SquashFS tools (`mksquashfs`) 56 | - `mkfs.fat` 57 | - [NASM](https://nasm.us) 58 | - Python 3 59 | - [Python `pefile`](https://pypi.org/project/pefile/) 60 | - [fatcat](https://github.com/Gregwar/fatcat) 61 | - [QPDF](http://qpdf.sourceforge.net) 62 | - [QEMU][qemu] and [OVMF][ovmf] (for testing) 63 | 64 | Clone this repo, run `make PDF=/path/to/your.pdf` and wait - a `bootable.pdf` will be produced. 65 | See above for boot instructions. 66 | 67 | Not passing `PDF=` to `make` will use the included sample PDF ([my CV](sample.pdf)). 68 | 69 | **Be sure check if it still works as a PDF on its own - unfortunately not all seem to be compatible.** 70 | 71 | ## How does it work? 72 | The main reason this works is that **the PDF header only needs to appear within the first 1024 bytes of a PDF file**. 73 | 74 | Given this, there are several components which allow the PDF to be bootable (and remain usable) in 3 distinct ways: 75 | BIOS, EFI and "indirect EFI" (EFI binary on another disk). 76 | 77 | ### BIOS booting 78 | In order to boot on a BIOS system, there must be an [MBR](https://en.wikipedia.org/wiki/Master_boot_record) boot sector 79 | at the start of the file (since it will be burned directly to disk). 80 | 81 | CVos' loader is based on Sebastian Plotz's [Minimal Linux Bootloader](http://sebastian-plotz.blogspot.com/2012/07/1.html), 82 | with modifications to allow a for PE header (required for booting as a standalone EFI binary, see below) to fit. 83 | 84 | The boot process looks like this: 85 | 1. BIOS loads the MBR and starts executing it as real-mode code 86 | 2. The main code for the loader resides beyond the MBR, so it loads that sector into memory and jumps into it 87 | 3. Main loader code loads the kernel into memory and jumps into it 88 | [as required by the Linux documentation](https://github.com/torvalds/linux/blob/master/Documentation/x86/boot.rst) 89 | 90 | Since the PDF must start within the first 1024 bytes of the file, it is inserted right after the end of the bootloader 91 | code (at offset `0x38a`). The size of the PDF in bytes is written as a 32-bit unsigned integer just before this 92 | (at `0x386`) so that Linux knows how to extract it later. 93 | 94 | The offset of the kernel (LBA) is also calculated and written in the boot code at assembly time, since it comes after 95 | the PDF. 96 | 97 | ### EFI booting 98 | In order to be bootable on an EFI system, the disk must contain a FAT filesystem (in this case a FAT12 just large enough 99 | to fit the kernel). UEFI firmwares will automatically look for an EFI binary at `/EFI/Boot/bootx64.efi` on and load it. 100 | 101 | Since the kernel can be built as an EFI binary ([EFISTUB](https://www.kernel.org/doc/Documentation/efi-stub.txt)), it is 102 | placed as `/EFI/Boot/bootx64.efi` on the FAT12. The BIOS loader (as described above) loads the kernel directly from its 103 | position in the FAT12. 104 | 105 | ### Indirect EFI booting 106 | The [PE](https://docs.microsoft.com/en-us/windows/desktop/debug/pe-format) header (EFI binaries are PE's) can be 107 | (almost\*) arbitrarily placed within the file - a 32-bit value at `0x3c` points to the main header. 108 | 109 | In the PDF, the header is essentially a copy of the [kernel's EFISTUB PE header][kernel_pe] with the physical offsets 110 | modified to point to their locations in the PDF (past the actual PDF content). 111 | 112 | The UEFI can then load the kernel's EFISTUB code appropriately if the file is executed as an EFI binary. 113 | 114 | \*: *UEFI firmwares don't seem to like the header being placed after the lowest loaded virtual address of sections 115 | in the binary. Since Linux loads its initial EFI code at `0x200`, the PE header must be within the first 512 bytes of 116 | the file, leading to the requirement to relocate most of the BIOS loader code.* 117 | 118 | ### Finding and mounting the root filesystem 119 | Once the kernel has been executed, a simple `initramfs` (embedded into the kernel) locates and mounts the root filesystem. 120 | 121 | As described above, the first partition in the MBR is the FAT12 acting as an "ESP". The second partition contains a 122 | [squashed](https://www.kernel.org/doc/Documentation/filesystems/squashfs.txt), 123 | [Alpine Linux](https://alpinelinux.org)-based root filesystem. 124 | 125 | When loaded, the `initramfs` searches available disks for an MBR disk signature of `0xcafebabe` - this signature is 126 | hardcoded into the MBR of the image. This works for BIOS and UEFI booting. 127 | 128 | If the PDF was booted as an EFI binary ("indirect"), the disk signature will not be directly available. The `initramfs` 129 | will then try mounting each FAT filesystem on any disks on the system, looking for the magic value in 130 | `/EFI/Boot/bootx64.efi`, if the file exists. If the signature is found, a loop device is set up representing the same 131 | "disk" as if the PDF had been booted directly. 132 | 133 | At this point, the root filesystem is mounted as the lower portion of an 134 | [OverlayFS](https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt), with the upper filesystem being a `tmpfs`. 135 | This is because the SquashFS is read-only. With the overlay, any writes will go into RAM, similar to many live CDs. 136 | 137 | ### "Extracting" and showing the PDF 138 | The last thing the `initramfs` does before switching root to the Alpine rootfs is to extract the PDF to a file that can be 139 | read by the PDF viewer. The size of the PDF is read from the value written to `0x386` in the PDF, and `dd` is used to 140 | extract it to `/embedded.pdf`. 141 | 142 | Once Alpine's init system takes over, an X server is started, a welcome message is shown and the PDF viewer is opened on 143 | `/embedded.pdf`. 144 | 145 | ### Building initramfs BusyBox and MuPDF 146 | In order to reduce the size of the initramfs as much as possible, a customised static BusyBox binary is built. 147 | A customised build of [MuPDF](https://mupdf.com) is also used as the PDF viewer in the rootfs. 148 | 149 | In order to reduce the size of BusyBox as much as possible, it is built against [musl](https://www.musl-libc.org), which, 150 | for the same reason, is used by Alpine as its implementation of libc. Since most Linux distributions ship with glibc, 151 | it makes sense to build BusyBox in an Alpine chroot environment. 152 | 153 | Although a MuPDF package [is available](https://pkgs.alpinelinux.org/package/edge/main/x86_64/mupdf) for Alpine, this 154 | build ships with over 40MiB of fonts, while many PDF's embed their fonts. To reduce this overhead, a customised MuPDF 155 | Alpine package is built in the same chroot environment as BusyBox. 156 | 157 | This buildroot environment (separate from the root filesystem) is created using a slightly modified 158 | [`alpine-make-rootfs`](https://github.com/alpinelinux/alpine-make-rootfs). 159 | 160 | ### Building the root filesystem 161 | The root filesystem is built via `alpine-make-rootfs`, as with the buildroot. The necessary packages are installed, a 162 | chroot script copies the [OpenRC](https://github.com/OpenRC/openrc) services + tweaked messages (`motd` etc.) and 163 | enables the services to start on boot. 164 | 165 | ### Producing the PDF / image 166 | Once all of the necessary components have been built (initramfs BusyBox, kernel, MuPDF and root filesystem), a Python 167 | script, `mk_disk.py`, combines them with the MBR code, creating the FAT12 file system and calculating all necessary 168 | offsets to produce the final bootable PDF. 169 | 170 | ## Overhead 171 | - Kernel is ~6MiB (XZ-compressed, including ~0.5MiB `initramfs`) 172 | - XZ-compressed SquashFS root filesystem is ~13MiB 173 | - About ~20MiB of the *compressed* rootfs is saved by using the customised build of MuPDF for Alpine 174 | 175 | The total size of the bootable PDF is then: original PDF size + ~19MiB 176 | 177 | [ovmf]: https://github.com/tianocore/tianocore.github.io/wiki/OVMF 178 | [qemu]: https://www.qemu.org 179 | [kernel_pe]: https://github.com/torvalds/linux/blob/9fb67d643f6f1892a08ee3a04ea54022d1060bb0/arch/x86/boot/header.S#L100 180 | -------------------------------------------------------------------------------- /alpine-make-rootfs: -------------------------------------------------------------------------------- 1 | #!/bin/sh 2 | # vim: set ts=4: 3 | #---help--- 4 | # Usage: alpine-make-rootfs [options] [--] [