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List:       linuxbios
Subject:    [coreboot] Duplicate BIOS flash mapping - ITE EC RAM
From:       Github User <githubhun () freemail ! hu>
Date:       2021-04-30 4:41:08
Message-ID: AzfZ8g.ayQ49YJ41zCs.pMvQTl2OA2KkNeIsNNto () freemail ! hu
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Hi All,
I try port an old AMD Fam15h KaveriPI board to Coreboot, and to enable the EC \
properly (proprietary IT8586e, with its own FW stored in E-Flash - similar to IT5570) \
the EC would need to map its internal RAM to 0xff000000 in host memory.   However, \
currently this (host) RAM region is occupied by CB despite the fact, that normally - \
considering a 8MB flash size - CB flash image should be mapped to 0xff800000 only. \
The whole CB image of course is also mapped to that address (reading via DD from \
/dev/mem), but why do I have this duplicate mapping? More interestingly if I use a \
4MB flash chip and image size (CB normally mapped to 0xffc00000) I see the CB image \
mapped four times (at addresses 0xff00.. 0xff40.., 0xff80.., 0xffc0..). Any thoughts \
why this redundant mapping could there be and how to eliminate?

PS: the EC provides some kind of flexibility to relocate its RAM to  host ram mapping \
via LDN=0xf, SMFI registers (within 0xfexx.. - 0xffxx.. region in host), but despite \
trying to reserve any 4K region within that range in CB (+setting Hudson LPC to \
decode + reserve this memory region also in ACPI) - there are only empty data (0xff) \
visible in host memory.

Thanks,
Githubhun


[Attachment #5 (text/html)]

Hi All,<br />
I try port an old AMD Fam15h KaveriPI board to Coreboot, and to enable the EC \
properly (proprietary IT8586e, with its own FW stored in E-Flash - similar to IT5570) \
the EC would need to map its internal RAM to 0xff000000 in host memory.&#160; \
However, currently this (host) RAM region is occupied by CB despite the fact, that \
normally - considering a 8MB flash size - CB flash image should be mapped to \
0xff800000 only. The whole CB image of course is also mapped to that address (reading \
via DD from /dev/mem), but why do I have this duplicate mapping?<br /> More \
interestingly if I use a 4MB flash chip and image size (CB normally mapped to \
0xffc00000) I see the CB image mapped four times (at addresses 0xff00.. 0xff40.., \
0xff80.., 0xffc0..).<br /> Any thoughts why this redundant mapping could there be and \
how to eliminate?<br /> <br />
PS: the EC provides some kind of flexibility to relocate its RAM to&#160;host ram \
mapping via LDN=0xf, SMFI registers (within 0xfexx.. - 0xffxx.. region in host), but \
despite trying to reserve any 4K region within that range in CB (+setting Hudson LPC \
to decode + reserve this memory region also in ACPI) - there are only empty data \
(0xff) visible in host memory.<br /> <br />
Thanks,<br />
Githubhun



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