On Jan 23, 2013, at 1:18 PM, cruxpot <[email protected]> wrote:
> Since my last email, I was able to write platform-specific code that can
> access the firmware from an X64 platform and extract it. Is there a way to
> extract and/or dissect the FV or FVs that have the SEC and PEI Core for a
> given .FD or .ROM file (assume I have no corresponding .FDF file and do not
> know the structure)? The goal here is to do some integrity checks on key
> files or modules that are consistent and do not change (unless they are
> updated). I want to ignore sections of the ROM that have volatile data that
> changes frequently such as firmware settings changes, the clock, etc.. Thanks.
>
There is a command line build tool to dump FVs called VolInfo, and you may find
this useful.
https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/BaseTools/Source/C/VolInfo/
I think you are stuck searching the FD for FV headers with the _FVH signature,
and checksums etc. The FV should define how bigt it is.
https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/MdePkg/Include/Pi/PiFirmwareVolume.h
In terms of code at the reset vector for ARM the reset vector is usually in the
ZeroVector of the FV that starts at the magic address. For IA32/X64 there is a
magic file name GUID called EFI_FFS_VOLUME_TOP_FILE_GUID that implies the last
byte of the file is the last byte of the FV. This backwards alignment is used
to get code at the magic 0xFFFFFFF0 reset vector address.
https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/MdePkg/Include/Guid/FirmwareFileSystem2.h
SEC, PEI Core, etc are file types in the FV.
Thanks,
Andrew Fish
>
> On Mon, Dec 3, 2012 at 5:35 PM, Andrew Fish <[email protected]> wrote:
> UEFI is focused on defining the interfaces to option ROMs and OS loaders, and
> pushing policy decisions, where possible, in the platform firmware. UEFI
> tends to not define how the construct the platform Firmware. The UEFI PI
> specs go into more detail of firmware construction, but mostly so modules can
> interoperate. PI does not focus on things that are higher level platform
> firmware features.
>
> The PI terminology is FD (Flash Device) and there is no way to access the FD
> programmatically. The platform firmware produces FVs (Firmware Volumes) out
> of the FD in PEI (memory discovery/S3) and DXE (EFI services) phases. The FV
> containing the SEC and PEI Core are often executed directly from the FD, but
> most other FVs are compressed. This is all done via platform specific code.
>
> Andrew Fish
>
>
> On Dec 3, 2012, at 2:24 PM, cruxpot wrote:
>
> > Hi there,
> >
> > I am wondering if there are any calls in edk2 or the UEFI spec to locate
> > the system's BIOS code and dump it to disk or some other medium. I want to
> > implement this in a UEFI driver. I have seen plenty of information
> > regarding option ROMs in the spec and driver guide but not on the BIOS
> > code. If I missed it, please point me to the right resources.
> >
> > Thanks
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