diff --git a/Documentation/mainboard/lenovo/Sandy_Bridge_series.md b/Documentation/mainboard/lenovo/Sandy_Bridge_series.md index 0b833f5cc84c..dbbbbeef30c3 100644 --- a/Documentation/mainboard/lenovo/Sandy_Bridge_series.md +++ b/Documentation/mainboard/lenovo/Sandy_Bridge_series.md @@ -33,9 +33,7 @@ usable by coreboot. * ROM chip size should be set to 8MiB. -```eval_rst -Please also have a look at :doc:`../../flash_tutorial/index`. -``` +Please also have a look at the [flashing tutorial] ## Flash layout There's one 8MiB flash which contains IFD, GBE, ME and BIOS regions. @@ -46,3 +44,26 @@ region. The update is then written into the EC once. [fl]: flashlayout_Sandy_Bridge.svg +## Reducing Intel Managment Engine firmware size + +It is possible to reduce the Intel ME firmware size to free additional +space for the `bios` region. This is usually refered to as *cleaning the ME* or +*stripping the ME*. +After reducing the Intel ME firmware size you must modify the original IFD +and then write a full ROM using an [external programmer]. +Have a look at the [me_cleaner] for more information. + +Tests on Lenovo X220 showed no issues with a stripped ME firmware. + +**Modified flash layout:** + +![][fl2] + +[fl2]: flashlayout_Sandy_Bridge_stripped_me.svg + +The overall size of the `gbe`, `me,` `ifd` region is less than 128KiB, leaving +the remaining space for the `bios` partition. + + +[me_cleaner]: ../../northbridge/intel/sandybridge/me_cleaner.md +[external programmer]: ../../flash_tutorial/index.md diff --git a/Documentation/mainboard/lenovo/flashlayout_Sandy_Bridge_stripped_me.svg b/Documentation/mainboard/lenovo/flashlayout_Sandy_Bridge_stripped_me.svg new file mode 100644 index 000000000000..d8d8213d1214 --- /dev/null +++ b/Documentation/mainboard/lenovo/flashlayout_Sandy_Bridge_stripped_me.svg @@ -0,0 +1,74 @@ + + + + + + + + + + + + + + IFD + + + + + + + + + + + + BIOS + + + + + + + + + + + + GBE + + + + 0x000000 + + + 0x001000 + + + 0x003000 + + + 0x020000 + + + 0x800000 + + + + + Flash #0 + + + + + + + + + + + + ME + + + diff --git a/Documentation/northbridge/intel/sandybridge/me_cleaner.md b/Documentation/northbridge/intel/sandybridge/me_cleaner.md index 1086e7e09199..b457dcdd3c68 100644 --- a/Documentation/northbridge/intel/sandybridge/me_cleaner.md +++ b/Documentation/northbridge/intel/sandybridge/me_cleaner.md @@ -5,7 +5,7 @@ from the ME firmware partition. In this state the ME errors out and doesn't operate any more. **Using a 'cleaned' ME partition may lead to issues and its use should be -carefully evaulated.** +carefully evaluated.** ## Observations with 'cleaned' ME @@ -18,3 +18,67 @@ carefully evaulated.** Always test with unmodified IFD and ME section before reporting bugs to the coreboot project. + +## Tutorial reducing the Intel ME firmware size + +By default the cleaned ME firmware will still occupy the same space in +the firmware image. It's possible to change the firmware partition layout +and reclaim the space for the use by coreboot. +With the reduced Intel ME firmware the `ifd`, `gbe` and `me` regions require +less than 128 KiB of space in the ROM, which leaves the remaining for the +`bios` region. + +This tutorial will guide you through the steps necessary. + +### 1. Obtain a full ROM + +You need a full and working ROM with a full Intel ME firmware. + +### 2. Running me_cleaner + +You need to run the *me_cleaner* on a full ROM, here called `fulldump.rom`: +The full ROM contains: +* IFD +* fully working Intel ME +* GbE (optional) +* BIOS (any firmware) + +Running the command will generate two new files: +```console +./util/me_cleaner/me_cleaner.py -D patched_desciptor.bin -M stripped_me.bin fulldump.rom -t -r -S +``` + +The generated files are: +* a patched IFD called `patched_desciptor.bin` +* stripped Intel ME called `stripped_me.bin` + +The patched IFD has the *AltMeDisable* bit set and a modified flash layout. + + +*Note:* coreboot allows to select `CONFIG_ME_CLEANER` as part of the +build-process, but that doesn't rework the flash layout, it only removes +files from ME and sets the *AltMeDisable*-bit. + +### 3. Build coreboot + +1. Now include the two new files from the previous step into coreboot's + build system. +2. Make sure to also increase the CBFS size + * 0x7E0000 for a 8MiB ROM + * 0xBE0000 for a 12MiB ROM + * 0xFE0000 for a 16MiB ROM +3. Make sure to **not** enable me_cleaner in Kconfig again as + you have already run it + +### 4. Flashing the ROM + +As you have modified the layout you need to write the **full ROM** to flash +using an [external programmer]. +Make sure to include all partitions into the ROM: +* IFD +* EC (might be unused) +* GbE (might be unused) +* ME +* BIOS + +[external programmer]: ../../../flash_tutorial/index.md