Re: [Xen-devel] Re: [PATCH][VTD] pci mmcfg patch for x86-64 -version 3

[Konrad Rzeszutek <konrad@xxxxxxxxxxxxxxx>]

> >>Oh, and one more thing I remembered just now: Linux verifies the mmcfg
> >>values it gets from ACPI against the E820 map - shouldn't Xen 
> >>do this too?
> >
> >My original intent was to keep mmconfig-shared.c and mmconfig_64.c as 
> >closely to Linux as possible.  However, I soon found out
> >including everything in mmconfig-shared.c involved pulling in a lot of code 
> >from Linux.
> 
> Understandable. But this particular check may save us from dying on systems
> where Linux works. And it shouldn't be that much code that needs adding

My recollection of this was that the check was added for buggy pre-release
Intel boxes (the address that was coded in the ACPI MMCONFIG table was
completly bogus). Follow this link for more details:
http://lkml.indiana.edu/hypermail/linux/kernel/0605.2/0923.html

I honestly can't remember anymore the details of the E820 check, but the
check isn't that difficult:

Read the addresses and make sure they are the host E820 as reserved.

> here if you restrict this to the E820 check; I'm not certain how significant
> the ACPI check is (which would require Dom0 assistance in my opinion, as
> it requires the ACPI interpreter to be available).


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