Re: [PATCH 1/2] x86, ioapic: Reserve only 128 bytes for IOAPICs

H. Peter Anvin
2011-08-26T01:43:13Z

On 08/25/2011 05:17 PM, Bjorn Helgaas wrote:
>
> If the OS allocated the next 128 bytes to another device, it sounds
> like it would cause a conflict on Intel boxes. This must be an area
> that differs between vendors. I haven't seen a spec that mentions 256
> bytes as the required minimum MMIO size for IOAPICs, and apparently
> the AMD IOAPIC decodes 240 bytes or fewer.
>

For what it's worth, it's probably a bad idea on x86 for the OS to
allocate addresses in the 0xFExxxxxx range...

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.