[flashrom] flashrom Rangeley with WINDBOND25Q64

[Marc Jones]

On Tue, Aug 12, 2014 at 3:07 PM, Stefan Tauner
<stefan.tauner at alumni.tuwien.ac.at> wrote:
> On Tue, 12 Aug 2014 12:15:53 -0400 (EDT)
> wenw at adiengineering.com wrote:
>
>> 0x54: 0x000f0000 FREG0: Warning: Flash Descriptor region (0x00000000-0x0000ffff) is read-only.
>> 0x58: 0x07ff0200 FREG1: BIOS region (0x00200000-0x007fffff) is read-write.
>
> Hello Wen,
>
> it seems like this bogus kind of descriptor layout becomes popular. Let
> me explain in case you don't understand: The descriptor region in the
> first 4kB of the flash chip - similar to a partition table - defines
> (among other things) which parts of the flash chip are used for what
> components. Usually all addresses of the flas chip are covered by this
> but sometimes vendor forget to do this properly - or do have no use for
> it.
>
> The problem (for flashrom) is that the Intel SPI controllers forbid
> accesses to addresses that are not covered by the descriptor regions -
> like 0x00010000 to 0x001FFFFF in this case, which is almost a quarter
> of the flash chip - but flashrom tries to read the whole chip
> nevertheless (for good reasons).
>
> So flashrom works more or less as expected on that board as far as you
> have tested it. That result is probably not very useful to you, but
> fine with me for now... :)
>
> If you want to be able to write to the BIOS region, you
> will also need my layout patches (they are also on github), and also
> set the read_all_first variable in doit() in flashrom.c to 0.
> I'd welcome such further tests of course but please be prepared for
> recovery if need be.
>
> I have included Marc from Sage because I guess he may be able to tell
> us about the reason for this.

I recommend that you use and external programmer to re-write the
descriptor as you need for development. The coreboot ifdtool is
helpful for this. (someone want to post a how-to on the wiki?)

Marc


> --
> Kind regards/Mit freundlichen Grüßen, Stefan Tauner