Libreboot – Binary Blob Reduction Policy English | Deutsch | українська Return to index Article published by: Leah Rowe Date of publication: 4 January 2022 (updated 15 November 2022) << < Prev Next > >> Free as in freedom! [link] Libreboot’s policy is to provide as much software freedom as possible to each user, on each and every bit of hardware supported, and to support as much hardware from coreboot as is feasible; what this means is that you should have the potential to study, modify and share all source code, documentation or other such resources that make Libreboot what it is. Put simply, you should have control of your own computing. The goal of Libreboot is to do exactly this, and help as many people as possible by automating the configuration, compilation and installation of coreboot for non-technical users, easing it further for the average user by providing user-friendly instructions for everything. Essentially, Libreboot is a coreboot distribution, in much the same way Alpine Linux is a Linux distribution! The purpose of this document it to outline how that is brought about, and how the project operates along this basis. This document is largely about the ideology and it is therefore (mostly) non-technical; for technical information, you can refer to the Libreboot build system documentation. Current project scope [link] The libreboot project is concerned with what goes in the main boot flash IC, but there are other pieces of firmware to take into consideration, as covered in the libreboot FAQ. Most critical of these are: Embedded controller firmware HDD/SSD firmware Intel Management Engine / AMD PSP firmware What is a binary blob? [link] A binary blob, in this context, is any executable for which no source code exists, that you cannot study and modify in a reasonable manner. By definition, all such blobs are proprietary in nature, and should be avoided if possible. For information about Intel Management Engine and AMD PSP, refer to the FAQ. Blob reduction policy [link] Default configurations [link] Coreboot, upon which Libreboot is based, is mostly libre software but does require certain vendor code on some platforms. A most common example might be raminit (memory controller initialisation) or video framebuffer initialisation. The coreboot firmware uses certain vendor code for some of these tasks, on some motherboards, but some motherboards from coreboot can be initialised with 100% libre source code, which you can inspect, and compile for your use. Libreboot deals with this situation in a strict and principled way. The nature of this is what you’re about to read. The libreboot project has the following policy: If free software can be used, it should be used. For example, if VGA ROM initialization otherwise does a better job but coreboot has libre init code for a given graphics device, that code should be used in libreboot, when building a ROM image. Similarly, if memory controller initialization is possible with vendor code or libre code in coreboot, the libre code should be used in ROMs built by the Libreboot build system, and the vendor raminit code should not be used; however, if no libre init code is available for said raminit, it is permitted and Libreboot build system will use the vendor code. Some nuance is to be observed: on some laptop or desktop configurations, it’s common that there will be two graphics devices (for example, an nvidia and an intel chip, using nvidia optimus technology, on a laptop). It may be that one of them has libre init code in coreboot, but the other one does not. It’s perfectly acceptable, and desirable, for libreboot to support both devices, and accomodate the required vendor code on the one that lacks native initialization. An exception is made for CPU microcode updates: they are permitted, and in fact required as per libreboot policy. These updates fix CPU bugs, including security bugs, and since the CPU already has non-libre microcode burned into ROM anyway, the only choice is either x86 or broken x86. Thus, libreboot will only allow coreboot motherboard configurations where microcode updates are enabled, if available for the CPU on that motherboard. Releases after 20230423 will provide separate ROM images with microcode excluded, alongside the default ones that include microcode. Intel Management Engine: in the libreboot documentation, words must be written to tell people how to neuter the ME, if possible on a given board. The me_cleaner program is very useful, and provides a much more secure ME configuration. Such vendor files should never be deleted, even if they are unused. In the coreboot project, a set of 3rdparty submodules are available, with vendor code for init tasks on many boards. These must all be included in libreboot releases, even if unused. That way, even if the Libreboot build system does not yet integrate support for a given board, someone who downloads libreboot can still make changes to their local version of the build system, if they wish, to provide a configuration for their hardware. Generally speaking, common sense is applied. For example, an exception to the minimalization might be if vendor raminit and libre raminit are available, but the libre one is so broken so as to be unusable. In that situation, the vendor one should be used instead, because otherwise the user might switch back to an otherwise fully proprietary system, instead of using coreboot (via libreboot). Some freedom is better than none. Libreboot’s pragmatic policies will inevitably result in more people becoming coreboot developers in the future, by acting as that crucial bridge between it and non-technical people who just need a bit of help to get started. Configuration [link] The principles above should apply to default configurations. However, libreboot is to be configurable, allowing the user to do whatever they like. It’s natural that the user may want to create a setup that is less libre than the default one in libreboot. This is perfectly acceptable; freedom is superior, and should be encouraged, but the user’s freedom to choose should also be respected, and accomodated. In other words, do not lecture the user. Just try to help them with their problem! The goal of the libreboot project is simply to make coreboot more accessible for otherwise non-technical users. Examples of Libreboot policy in action [link] Context is everything, so to make the above picture more clear, here are a few examples of how this very policy is implemented in Libreboot: On many laptops, it is possible to have both Intel graphics and a dedicated graphics card enabled; more about Intel graphics is covered below. We could provide the VGA ROM for those extra chips, e.g. Nvidia graphics chips, but we don’t. We configure the machines in such a way where the Intel graphics is used, exclusively, so the dedicated GPU may as well be turned off, and it is turned off in such circumstances. The Intel graphics provide good enough performance and reliable operation for most people, and native initialisation code is available from coreboot to make use of the Intel GPU at boot time. Newer Intel platforms have Intel ME, which is a coprocessor inside the machine that handles many functions including certain power management, and it can provides useful remote management features with Intel AMT for example. This is a giant 5MB+ section in the flash, and the ME has full access to your RAM and other peripherals; more is documented about this in the Libreboot FAQ. On older ME4-based platforms such as Intel GM45 platforms, e.g. ThinkPad X200/T400, we remove the ME firmware entirely from the flash, leaving the Intel ME in a permanent reset loop. On Intel Sandybridge and up, we include ME firmware when building, or provide a script to insert it via vendor download on release images, but Libreboot’s build system automatically runs the me cleaner software, which removes most of the features from the ME, including its kernel and networking stack, leaving only a rump (dare we say, ROMP) of initialisation code in the ME; essentially, the configuration is equivalent to running coreboot without a payload, where it does nothing other than initialise itself, because that is all the ME does in this configuration, initialise itself but not actually run anything. ME Cleaner is required, instead of full removal, because the machines don’t boot reliably without at least the BUP/ROMP modules present in flash. On Intel Haswell platform (Intel 4th gen), vendor firmware is available for memory controller initialisation, called the Intel MRC or System Agent. We previously included this in Libreboot; nowadays, we have free initialisation code written by Angel Pons. The libre code, called NRI (Native RAM Initialisation) still has a few bugs, such as lack of ECC support, and the MRC also does other things such as initialise certain peripherals. The Haswell machines can be configured in EHCI or XHCI mode for USB ports at startup, and the latter means that you need xHCI support in whatever you’re using such as Linux, but also payloads such as U-Boot or GRUB. SeaBIOS and GRUB have stable xHCI support (we have to patch GRUB to have it because otherwise upstream doesn’t have it). U-Boot’s xHCI support is quite buggy, at least as of November 2024; when tested, it looks like the EHCI mode doesn’t work on NRI, only MRC. Now, to get more stable U-Boot support when using USB devices, we could use the MRC and set the machine in EHCI mode at startup; an option exists for it in coreboot. Ditto, we could have ECC support (useful on the Dell Precision T1700, which Libreboot supports!) - it was decided that these issues are quite minor so the free initialisation code is used, and we no longer provide the MRC. Libreboot provides native graphics initialisation on most Intel hardware, provided by coreboot. This replaces the Intel VGA ROM; called libgfxinit, coreboot’s native code is far from perfect because many legacy VGA functions simply do not work so it can be a challenge to get old, legacy operating systems working, even if they had full driver support on a given machine when running the vendor BIOS. Libgfxinit otherwise provides a sensible framebuffer implementation from coreboot, which Linux and BSD systems know how to use, and you can use KMS on these systems instead of calls to VGA in the BIOS, to mitigate this issue. It was decided a long time ago that, when available, the native initialisation should be used, when it is stable and Linux/BSD systems work reliably. There is only one exception: the ThinkPad T480 currently doesn’t work with libgfxinit in Libreboot, at least as of November 2024, so the Intel VGA ROM is used instead. On RK3399-based Chromebooks, it is possible to load a HDCP blob, which could be convenient for easy access to DRM-based media. We simply do not use this blob on any machines, because it is completeley unnecessary for everyday operating of a free operating system. Free hardware [link] It is desirable to see a world where all hardware and software is libre, under the same ideology as the Libreboot project. Hardware!? Yes, hardware. RISC-V is a great example of a modern attempt at libre hardware, often called Open Source Hardware. It is a an ISA for the manufacture of a microprocessor. Many real-world implementations of it already exist, that can be used, and there will only be more. Such hardware is still in its infancy. We should start a project that will catalog the status of various efforts, including at the hardware level (even the silicon level). Movements like OSHW and Right To Repair are extremely important, including to our own movement which otherwise will typically think less about hardware freedoms (even though it really, really should!) One day, we will live in a world where anyone can get their own chips made, including CPUs but also every other type of IC. Efforts to make homemade chip fabrication a reality are now in their…