Re: [discuss] Re: 2.6.19-rc4: known unfixed regressions (v3)

From: Jeff Garzik
Date: Fri Nov 10 2006 - 08:58:14 EST


Linus Torvalds wrote:
We really should stop using MMCONFIG entirely, until we have a per-southbridge true knowledge of what the real decoding is. The BIOS tables for this are simply too damn unreliable.


FWIW: MMCONFIG is required for PCI domain support (or "PCI segments" as ACPI calls them). Only a few mass market OEM boxes exist that need this -- and they are all pretty new (Opteron multi-core) -- but more are coming.

I have a patch in -mm that works for this. Without the patch, my sata_mv card and the machine's built-in MPT-Fusion do not appear at all in PCI bus scans (nor do the associated hard drives) on this production HP box. So far these machines are rare, /usually/ with a BIOS switch to turn off PCI domains.

This says nothing about BIOS table reliability, of course. I agree that MMCONFIG probing is highly unreliable at present. Whitelisting "<2007" systems like Andi proposed may be the only option in some cases.

Jeff


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