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diff --git a/util/me_cleaner/README.md b/util/me_cleaner/README.md index 0ca3d32bf9..72c15986df 100644 --- a/util/me_cleaner/README.md +++ b/util/me_cleaner/README.md @@ -1,26 +1,44 @@ -# ME cleaner +# me_cleaner -A cleaner for Intel ME/TXE images. +Intel ME is a coprocessor integrated in all post-2006 Intel boards, for which +this [Libreboot page](https://libreboot.org/faq.html#intelme) has an excellent +description. The main component of Intel ME is Intel AMT, and I suggest you to +read [this Wikipedia page](https://en.wikipedia.org/wiki/Intel_Active_Management_Technology) +for more information about it. In short, Intel ME is an irremovable environment +with an obscure signed proprietary firmware, with full network and memory +access, which poses a serious security threat. +Even when disabled from the BIOS settings, Intel ME is active: the only way to +be sure it is disabled is to remove its firmware from the flash chip. -This tools removes any unnecessary partition from an Intel ME/TXE firmware, reducing -its size and its ability to interact with the system. -It should work both with coreboot and with the factory firmware. +Before Nehalem (ME version 6, 2008/2009) the ME firmware could be removed +completely from the flash chip by setting a couple of bits inside the flash +descriptor, without the need to reverse-engineer the ME firmware. -Currently this tool: - * Scans the FPT (partition table) and checks that everything is correct - * Removes any partition entry (except for FTPR) from FPT - * Removes any partition except for the fundamental one (FTPR) - * Removes the EFFS presence flag - * Corrects the FPT checksum - * Removes any non-essential LZMA or Huffman compressed module from the FTPR partition (pre-Skylake only) - * Relocates the remaining parts of the FTPR partition to the top of the ME region (pre-Skylake only) - * Checks the validity of the RSA signature of the FTPR partition +Starting from Nehalem the Intel ME firmware can't be removed anymore: without a +valid firmware the PC shuts off forcefully after 30 minutes. This project is an +attempt to remove as much code as possible from such firmware without falling +into the 30 minutes recovery mode. -Don't forget to power cycle your PC after flashing the modified ME/TXE image -(power off and power on, not just reboot). +me_cleaner currently works on most architectures, see [me_cleaner status](https://github.com/corna/me_cleaner/wiki/me_cleaner-status) (or [its discussion](https://github.com/corna/me_cleaner/issues/3)) +for more info about them. me_cleaner works also on the TXE and SPS firmware. -See the [current status](https://github.com/corna/me_cleaner/wiki/me_cleaner-status) -or [a more detailed description](https://github.com/corna/me_cleaner/wiki/How-does-it-work%3F) -of me_cleaner. +If you want to understand how me_cleaner works, you can read the ["How does it work?" page](https://github.com/corna/me_cleaner/wiki/How-does-it-work%3F). -Special thanks to Federico Amedeo Izzo for his help during the study of Intel ME. +If you want to apply me_cleaner on your platform I suggest you to read the +["How does it work?" page](https://github.com/corna/me_cleaner/wiki/How-does-it-work%3F) +and then follow the guide ["How to apply me_cleaner"](https://github.com/corna/me_cleaner/wiki/How-to-apply-me_cleaner). + +For pre-Skylake firmware (ME version < 11) this tool removes almost everything, +leaving only the two fundamental modules needed for the correct boot, ROMP and +BUP. The code size is reduced from 1.5 MB (non-AMT firmware) or 5 MB (AMT +firmware) to ~90 kB of compressed code. + +Starting from Skylake (ME version >= 11) the ME subsystem and the firmware +structure have changed, requiring substantial changes in me_cleaner. +The fundamental modules required for the correct boot are now four (rbe, kernel, +syslib and bup) and the minimum code size is ~300 kB of compressed code (from +the 2 MB of the non-AMT firmware and the 7 MB of the AMT one). + +This project is based on the work of the community; in particular I thank Igor +Skochinsky, for the core information about Intel ME and its firmware structure, +and Federico Amedeo Izzo, for its help during the study of Intel ME. |