GNU Boot – ich9utils

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# Introduction

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The `ich9utils` utility in Libreboot is used to manipulate Intel Flash Descriptors for ICH9M on laptops such as ThinkPad X200 or T400. Specifically, the `ich9gen` utility can generate 12KiB descriptor+GbE files for inserting into the start of a ROM, where everything after that is the BIOS region. These are special descriptors with the Intel ME region disabled, and Intel ME itself fully disabled.

ich9utils is handled by the `lbmk` (libreboot-make) build system, but the code itself is hosted in a separate repository. You can check the Git repositories linked on ../../contribute.html if you wish to download and use it.

It is very uncommon, on GM45/ICH9M systems, to have an Intel Flash Descriptor and GbE but without an Intel ME. On most of these systems (without Libreboot, Libreboot or coreboot), there is either descriptor+GbE+ME+BIOS or just BIOS, where on systems with just the BIOS region an Intel GbE NIC is not present. In Libreboot (and Libreboot), we provide descriptor+GbE images with Intel ME disabled and not present in the ROM; this enables the Intel GbE NIC to be used, while not having an Intel ME present. A consequence of this is that the malicious features of ME (such as AMT) are not present, however the Intel ME also handles TPM which is therefore disabled in this setup.

NOTE: If you accidentally flash a ROM without descriptor+GbE, it will still work but the Intel GbE NIC will be dysfunctional. If you do that, just boot up and correct the problem (and you can use a USB/cardbus/expresscard NIC or WiFi for internet if necessary). That is the main reason why `ich9utils` was written in the first place; it was already very possible to boot without an Intel ME by simply not having a descriptor or anything in ROM, just coreboot. The purpose of `ich9gen` specifically is to get the Intel GbE NIC working but without the Intel ME being enabled!

ICH9 based systems were the last generation that could be booted without an Intel ME. Future platforms (such as Sandybridge and Ivybridge) require an Intel ME since the ME on those platforms also handles power management and some minor initialization functions. On ICH9 based systems (such as X200 or T400) the Intel ME only handles AMT and TPM, and there’s no 30 minute timer (if you boot later platforms without an Intel ME and descriptor, or invalid Intel ME firmware, the system will either not boot or will turn off after 30 minutes per a watchdog reset timer).

More information about the ME can be found at http://www.coreboot.org/Intel_Management_Engine and http://me.bios.io/Main_Page.

Another project: http://io.netgarage.org/me/

# ich9utils

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You can find `ich9utils` on the Git page or you can download `lbmk` from the same page and run the following command in there:

./build module ich9utils

You can also find it in the source code tar archives, on Libreboot releases.

In `lbmk`, you can use the following command to generate descriptors:

./build build descriptors

The Libreboot build system will use the descriptors under `descriptors/ich9m` when building ROM images for these machines.

Alternatively, you can just clone `ich9utils` directly and run `make` in the directory, and run the `ich9gen` program directly.

# ICH9 show utility

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The ich9show utility outputs the entire contents of the descriptor and GbE regions in a given ROM image as supplied by the user. Output is in Markdown format (Pandoc variant) so that it can be converted easily into various formats. It could even be piped directly into pandoc!

# ICH9 gen utility

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When you simply run `ich9gen` without any arguments, it generates descriptor+GbE images with a default MAC address in the GbE region. If you wish to use a custom macaddress, you can supply an argument like so:

ich9gen –macaddress 00:1f:16:80:80:80

The above MAC address is just an example. It is recommended that you use the MAC address officially assigned to your NIC.

Three new files will be created:

- `ich9fdgbe_4m.bin`: this is for GM45 laptops with the 4MB flash chip.
- `ich9fdgbe_8m.bin`: this is for GM45 laptops with the 8MB flash chip.
- `ich9fdgbe_16m.bin`: this is for GM45 laptops with the 16MB flash chip.

These files contain the descriptor+GbE region and are suitable for systems that have an Intel GbE NIC present. The flash regions (as defined by the Intel Flash Descriptor) are set read-write which means that you can also re-flash using `flashrom -p internal` in your operating system running on that machine. This is the default setup used when Libreboot’s build system compiles ROM images.

Alternative versions of these files are also created, which have `ro` in the filename. If you use those versions, all flash regions (as defined by the Intel Flash Descriptor) will be set to read only. This can be useful, for security purposes, if you wish to ensure that malicious software in your operating system cannot simply re-flash new firmware.

The region setup created by these descriptors is as follows:

- First 4KiB of flash is: Intel Flash Descriptor
- Next 8KiB after Descriptor: Intel GbE region
- Rest of the flash, after GbE: BIOS region (BIOS region will have Libreboot)

The GbE region contains configuration data for your Intel GbE NIC. You can find information about this in Intel datasheets, and it is very well described in the `ich9utils` source code.

Assuming that your Libreboot image is named libreboot.rom, copy the file to where libreboot.rom is located and then insert the descriptor+gbe file into the ROM image.

For 16MiB flash chips:

dd if=ich9fdgbe_16m.bin of=libreboot.rom bs=12k count=1 conv=notrunc

For 8MiB flash chips:

dd if=ich9fdgbe_8m.bin of=libreboot.rom bs=12k count=1 conv=notrunc

For 4MiB flash chips:

dd if=ich9fdgbe_4m.bin of=libreboot.rom bs=12k count=1 conv=notrunc

If you wish to have read-only flash (write protected flash), substitute the above examples with descriptor+GbE images that have `ro` in the filename. RO here means read only, not Romania!

The above commands assume that in coreboot you have specified the CBFS size as no more than the size of the flash, minus 12KiB.

NOTE: `ich9gen` also generates descriptors without a GbE region, where in those descriptors the Intel GbE is not specified. Those are highly experimental, and theoretical since no such system exists in the wild where ICH9 is used, no Intel GbE NIC present and descriptor present; on such systems, the vendor will just supply a descriptor-less setup. Those GbE-less descriptor images created by `ich9gen` are only 4KiB in size, and should never be used except for fun, like, basically shits and/or giggles.

For shits and giggles, R500 ROM images in Libreboot use these no-GbE descriptor images generated by ich9gen. However, a descriptorless setup would also work just fine. ThinkPad R500 doesn’t have an Intel PHY in it, and it instead uses a Broadcom NIC for ethernet. In descriptorless mode, ICH9M works very similarly to older ICH7 chipsets.

Your libreboot.rom image is now ready to be flashed on the system. Refer back to ../install/#flashrom for how to flash it.

## Write-protecting the flash chip

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The `ich9gen` utility (see below) generates two types of descriptor+GbE setup:

- read-write
- read-only

Read on for more information. Use the `ro` files mentioned below, and your flash will be read-only in software (you can still externally re-flash and read the contents of flash).

For ease of use, Libreboot provides ROMs that are read-write by default. In practise, you can boot a Linux kernel with access to lower memory disabled which will make software re-flashing impossible (unless you reboot with such memory protections disabled, e.g. `iomem=relaxed` kernel parameter).

# ICH9 deblob utility

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This was the tool originally used to disable the ME on X200 (later adapted for other systems that use the GM45 chipset). ich9gen now supersedes it; ich9gen is better because it does not rely on dumping the factory.rom image (whereas, ich9deblob does).

Simply speaking, `ich9deblob` takes an original dump of the boot flash, where that boot flash contains a descriptor that defines the existence of Intel ME, and modifies it. The Intel Flash Descriptor is modified to disable the ME region. It disables the ME itself aswell. The GbE region is moved to the location just after the descriptor. The BIOS region is specified as being after the descriptor+GbE regions, filling the rest of the boot flash.

The GbE region is largely unedited when using this utility.

Run it like so, with `factory.rom` in the same directory:

./ich9deblob

The `factory.rom` file is your dump of the vendor boot flash. Older versions of this utility have this file name hardcoded, and for compatibility reasons it will still work in this manner. However, you can now specify your own file name.

For example:

./ich9deblob lenovo.rom

A 12kiB file named deblobbed_descriptor.bin will now appear. Keep this and the factory.rom stored in a safe location! The first 4KiB contains the descriptor data region for your system, and the next 8KiB contains the gbe region (config data for your gigabit NIC). These 2 regions could actually be separate files, but they are joined into 1 file in this case.

A 4KiB file named deblobbed_4kdescriptor.bin will alternatively appear, if no GbE region was detected inside the ROM image. This is usually the case, when a discrete NIC is used (eg Broadcom) instead of Intel. Only the Intel NICs need a GbE region in the flash chip.

Assuming that your Libreboot image is named libreboot.rom, copy the deblobbed_descriptor.bin file to where libreboot.rom is located and then run:

dd if=deblobbed_descriptor.bin of=libreboot.rom bs=12k count=1 conv=notrunc

Alternatively, if you got a the deblobbed_4kdescriptor.bin file (no GbE defined), do this:

dd if=deblobbed_4kdescriptor.bin of=libreboot.rom bs=4k count=1 conv=notrunc

(it’s very unlikely that you would ever see this. Descriptor without GbE is very rare, probably non-existant, but theoretically possible and this functionality is implemented based on Intel datasheets)

The utility will also generate 4 additional files:

- `mkdescriptor.c`
- `mkdescriptor.h`
- `mkgbe.c`
- `mkgbe.h`

These are self-written by `ich9deblob`. The `ich9gen` utility was created, based on this very functionality, with some tweaks made afterwards.

These are C source files that can re-generate the very same Gbe and Descriptor structs (from ich9deblob/ich9gen). To use these, place them in src/ich9gen/ in ich9deblob, then re-build. The newly build `ich9gen` executable will be able to re-create the very same 12KiB file from scratch, based on the C structs, this time without the need for a`factory.rom` dump!

You should now have a libreboot.rom image containing the correct 4K descriptor and 8K gbe regions, which will then be safe to flash. Refer back to index.html/#gm45 for how to flash it.

# demefactory utility

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This utility has never been tested, officially, but it should work.

This takes a `factory.rom` dump and disables the ME/TPM, but leaves the region intact. It also sets all regions read-write. Simply put, this means that you can use the original factory firmware but without the Intel ME enabled.

The ME interferes with flash read/write in flashrom, and the default descriptor locks some regions. The idea is that doing this will remove all of those restrictions.

Simply run (with `factory.rom` in the same directory):

./demefactory

It will generate a 4KiB descriptor file (only the descriptor, no GbE). Insert that into a factory.rom image (NOTE: do this on a copy of it. Keep the original factory.rom stored safely somewhere):

dd if=demefactory_4kdescriptor.bin of=factory_nome.rom bs=4k count=1 conv=notrunc

Use-case: a factory.rom image modified in this way would theoretically have no flash protections whatsoever, making it easy to quickly switch between factory/Libreboot in software, without ever having to disassemble and re-flash externally unless you brick the device.

The sections below are adapted from (mostly) IRC logs related to early development getting the ME removed on GM45. They are useful for background information. This could not have been done without sgsit’s help.

## Early notes

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- http://www.intel.co.uk/content/dam/doc/datasheet/io-controller-hub-10-family-datasheet.pdf page 230 mentions about descriptor and non-descriptor mode (which wipes out gbe and ME/AMT).
- See reference to HDA_SDO (disable descriptor security) strap connected GPIO33 pin is it on ICH9-M (X200). HDA_SDO applies to later chipsets (series 6 or higher). Disabling descriptor security also disables the ethernet according to sgsit. sgsit’s method involves use of ‘soft straps’ (see IRC logs below) instead of disabling the descriptor.
- and the location of GPIO33 on the x200s: (was an external link. Putting it here instead) ../../img/x200/gpio33_location.jpg - it’s above the number 7 on TP37 (which is above the big intel chip at the bottom)
- The ME datasheet may not be for the mobile chipsets but it doesn’t vary that much. This one gives some detail and covers QM67 which is what the X201 uses: http://www.intel.co.uk/content/dam/www/public/us/en/documents/datasheets/6-chipset-c200-chipset-datasheet.pdf

## Flash chips

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- X200 laptop (Mocha-1): ICH9-M overrides ifd permissions with a strap connected to GPIO33 pin (see IRC notes below)

  - The X200 can be found with any of the following flash chips:
    - ATMEL AT26DF321-SU 72.26321.A01 - this is a 32Mb (4MiB) chip
    - MXIC (Macronix?) MX25L3205DM2I-12G 72.25325.A01 - another 32Mb (4MiB) chip
    - MXIC (Macronix?) MX25L6405DMI-12G 41R0820AA - this is a 64Mb (8MiB) chip
    - Winbond W25X64VSFIG 41R0820BA - another 64Mb (8MiB) chip

  sgsit says that the X200s (Pecan-1) with the 64Mb flash chips are (probably) the ones with AMT (alongside the ME), whereas the 32Mb chips contain only the ME.

## Early development notes

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Start (hex) | End (hex) | Length (hex) | Area Name
--- | --- | --- | ---
00000000 | 003FFFFF | 00400000 Flas | h Image

00000000 00000FFF 00001000 Descriptor Region 00000004 0000000F 0000000C Descriptor Map 00000010 0000001B 0000000C Component Section 00000040 0000004F 00000010 Region Section 00000060 0000006B 0000000C Master Access Section 00000060 00000063 00000004 CPU/BIOS 00000064 00000067 00000004 Manageability Engine (ME) 00000068 0000006B 00000004 GbE LAN 00000100 00000103 00000004 ICH Strap 0 00000104 00000107 00000004 ICH Strap 1 00000200 00000203 00000004 MCH Strap 0 00000EFC 00000EFF 00000004 Descriptor Map 2 00000ED0 00000EF7 00000028 ME VSCC Table 00000ED0 00000ED7 00000008 Flash device 1 00000ED8 00000EDF 00000008 Flash device 2 00000EE0 00000EE7 00000008 Flash device 3 00000EE8 00000EEF 00000008 Flash device 4 00000EF0 00000EF7 00000008 Flash device 5 00000F00 00000FFF 00000100 OEM Section 00001000 001F5FFF 001F5000 ME Region 001F6000 001F7FFF 00002000 GbE Region 001F8000 001FFFFF 00008000 PDR Region 00200000 003FFFFF 00200000 BIOS Region

Start (hex) | End (hex) | Length (hex) | Area Name
--- | --- | --- | ---
00000000 | 003FFFFF | 00400000 Flas | h Image

00000000 00000FFF 00001000 Descriptor Region 00000004 0000000F 0000000C Descriptor Map 00000010 0000001B 0000000C Component Section 00000040 0000004F 00000010 Region Section 00000060 0000006B 0000000C Master Access Section 00000060 00000063 00000004 CPU/BIOS 00000064 00000067 00000004 Manageability Engine (ME) 00000068 0000006B 00000004 GbE LAN 00000100 00000103 00000004 ICH Strap 0 00000104 00000107 00000004 ICH Strap 1 00000200 00000203 00000004 MCH Strap 0 00000ED0 00000EF7 00000028 ME VSCC Table 00000ED0 00000ED7 00000008 Flash device 1 00000ED8 00000EDF 00000008 Flash device 2 00000EE0 00000EE7 00000008 Flash device 3 00000EE8 00000EEF 00000008 Flash device 4 00000EF0 00000EF7 00000008 Flash device 5 00000EFC 00000EFF 00000004 Descriptor Map 2 00000F00 00000FFF 00000100 OEM Section 00001000 00002FFF 00002000 GbE Region 00003000 00202FFF 00200000 BIOS Region

Build Settings
Flash Erase Size = 0x1000

It’s a utility called ‘Flash Image Tool’ for ME 4.x that was used for this. You drag a complete image into in and the utility decomposes the various components, allowing you to set soft straps.

This tool is proprietary, for Windows only, but was used to deblob the X200. End justified means, and the utility is no longer needed since the ich9deblob utility (documented on this page) can now be used to create deblobbed descriptors.

## GBE (gigabit ethernet) region in SPI flash

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Of the 8K, about 95% is 0xFF. The data is the gbe region is fully documented in this public datasheet: http://www.intel.co.uk/content/dam/doc/application-note/i-o-controller-hub-9m-82567lf-lm-v-nvm-map-appl-note.pdf

The only actual content found was:

00 1F 1F 1F 1F 1F 00 08 FF FF 83 10 FF FF FF FF
08 10 FF FF C3 10 EE 20 AA 17 F5 10 86 80 00 00
01 0D 00 00 00 00 05 06 20 30 00 0A 00 00 8B 8D
02 06 40 2B 43 00 00 00 F5 10 AD BA F5 10 BF 10
AD BA CB 10 AD BA AD BA 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 01 00 40 28 12 07 40 FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF D9 F0
20 60 1F 00 02 00 13 00 00 80 1D 00 FF 00 16 00
DD CC 18 00 11 20 17 00 DD DD 18 00 12 20 17 00
00 80 1D 00 00 00 1F

The first part is the MAC address set to all 0x1F. It’s repeated haly way through the 8K area, and the rest is all 0xFF. This is all documented in the datasheet.

The GBe region starts at 0x20A000 bytes from the *end* of a factory image and is 0x2000 bytes long. In Libreboot (deblobbed) the descriptor is set to put gbe directly after the initial 4K flash descriptor. So the first 4K of the ROM is the descriptor, and then the next 8K is the gbe region.

### GBE region: change MAC address

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According to the datasheet, it’s supposed to add up to 0xBABA but can actually be others on the X200. https://web.archive.org/web/20150912070329/https://communities.intel.com/community/wired/blog/2010/10/14/how-to-basic-eeprom-checksums

“One of those engineers loves classic rock music, so they selected 0xBABA”

In honour of the song Baba O’Reilly by The Who apparently. We’re not making this stuff up…

0x3ABA, 0x34BA, 0x40BA and more have been observed in the main Gbe regions on the X200 factory.rom dumps. The checksums of the backup regions match BABA, however. We think `0xBABA` is the only correct checksum, because those other, similar checksums were only ever found in the “backup” GbE regions on factory ROM dumps. In Libreboot, we simply use `0xBABA` and ensure that both 4KiB regions in GbE NVM have that checksum.

By default, the X200 (as shipped by Lenovo) actually has an invalid main gbe checksum. The backup gbe region is correct, and is what these systems default to. Basically, you should do what you need on the *backup* gbe region, and then correct the main one by copying from the backup.

Look at `ich9deblob.c` in ich9utils.

- Add the first 0x3F 16bit numbers (unsigned) of the GBe descriptor together (this includes the checksum value) and that has to add up to 0xBABA. In other words, the checksum is 0xBABA minus the total of the first 0x3E 16bit numbers (unsigned), ignoring any overflow.

## Flash descriptor region

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http://www.intel.co.uk/content/dam/doc/datasheet/io-controller-hub-9-datasheet.pdf from page 850 onwards. This explains everything that is in the flash descriptor, which can be used to understand what Libreboot is doing about modifying it.

How to deblob:

- patch the number of regions present in the descriptor from 5 - 3
- originally descriptor + bios + me + gbe + platform
- modified = descriptor + bios + gbe
- the next stage is to patch the part of the descriptor which defines the start and end point of each section
- then cut out the gbe region and insert it just after the region
- all this can be substantiated with public docs (ICH9 datasheet)
- the final part is flipping 2 bits. Halting the ME via 1 MCH soft strap and 1 ICH soft strap
- the part of the descriptor described there gives the base address and length of each region (bits 12:24 of each address)
- to disable a region, you set the base address to 0xFFF and the length to 0
- and you change the number of regions from 4 (zero based) to 2

There’s an interesting parameter called ‘ME Alternate disable’, which allows the ME to only handle hardware errata in the southbridge, but disables any other functionality. This is similar to the ‘ignition’ in the 5 series and higher but using the standard firmware instead of a small 128K version. Useless for Libreboot, though.

To deblob GM45, you chop out the platform and ME regions and correct the addresses in flReg1-4. Then you set meDisable to 1 in ICHSTRAP0 and MCHSTRAP0.

How to patch the descriptor from the factory.rom dump

- map the first 4k into the struct (minus the gbe region)
- set NR in FLMAP0 to 2 (from 4)
- adjust BASE and LIMIT in flReg1,2,3,4 to reflect the new location of each region (or remove them in the case of Platform and ME)
- set meDisable to 1/true in ICHSTRAP0 and MCHSTRAP0
- extract the 8k GBe region and append that to the end of the 4k descriptor
- output the 12k concatenated chunk
- Then it can be dd’d into the first 12K part of a coreboot image.
- the GBe region always starts 0x20A000 bytes from the end of the ROM

This means that Libreboot’s descriptor region will simply define the following regions:

- descriptor (4K)
- gbe (8K)
- bios (rest of flash chip. CBFS also set to occupy this whole size)

The data in the descriptor region is little endian, and it represents bits 24:12 of the address (bits 12-24, written this way since bit 24 is nearer to left than bit 12 in the binary representation).

So, x << 12 = address

If it’s in descriptor mode, then the first 4 bytes will be 5A A5 F0 0F.

## platform data partition in boot flash (factory.rom / lenovo bios)

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Basically useless for Libreboot, since it appears to be a blob. Removing it didn’t cause any issues in Libreboot. We think it’s just random data that the manufacturer can put there, to use in their firmware. Intel datasheets seem to suggest that the platform region serves no specific function except to provide a region in flash for the hardware manufacturer to use, for whatever purpose (probably just to store other configuration data, to be used by software running from the BIOS region as per region layout specified in the descriptor).

This is a 32K region from the factory image. It could be data (non-functional) that the original Lenovo BIOS used, but we don’t know.

It has only a 448 byte fragment different from 0x00 or 0xFF, on the X200 thinkpads that were tested.

Markdown file for this page: https://gnu.org/software/gnuboot/web/docs/install/ich9utils.md