On Wed, May 31, 2006 at 01:06:26AM +0200, Petr Vandrovec wrote:
> Jeremy Fitzhardinge wrote:
> >On Tue, 2006-05-30 at 16:41 -0400, [email protected] wrote:
> >
> >>On Tue, May 30, 2006 at 12:38:01PM -0700, Jeremy Fitzhardinge wrote:
> >>
> >>>[snip]
> >>>
> >>>So the MCFG entry is in the ACPI NVS region of the E820 table. Is this
> >>>bad?
> >>
> >>Not at all. The ACPI v3.0 specs mentions that:
> >>
> >>"ACPI NVS Memory. This range of addresses is in use or reserve by
> >>the system and must not be used by the operating system. This
> >>range is required to be saved and restored across an NVS sleep."
> >
> >
> >I actually misread the tables. It appears that MCFG (at 0x7f6e2e36) is
> >in ACPI Data (7f6d0000 - 7f6e3000). include/asm-i386/e820.h says that
> >memory marked as "E820_ACPI" can be reused as normal memory once the
> >ACPI tables have been read.
> >
> >Doesn't this mean that the MCFG memory could end up being used as
> >general system memory? That seems bad if MCFG memory is some kind of
> >MMIO space. Or is the comment simply wrong?
>
> Address where MCFG table lives is not important. What is important (and
> checked) is address of MMCONFIG reported by MCFG table... Unfortunately
> code does not bother with printing that address :-(
>
> Another problem is that code has hardcoded that MMCONFIG area is 256MB
> large. Unfortunately for the code PCI specification allows any power of two
> between 2MB and 256MB if vendor knows that such amount of busses (from 2 to
> 128) will be sufficient for system. With notebook it is quite possible
> that not full 8 bits are implemented for MMCONFIG bus number.
Patches to address this are always welcome :)
thanks,
greg k-h
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