Re: [PATCH 02/11] PCI: Try to allocate mem64 above 4G at first

H. Peter Anvin
2012-05-25T21:59:11Z

On 05/25/2012 02:55 PM, Bjorn Helgaas wrote:
>
> I think we actually have a separate bug here. On 64-bit non-x86
> architectures, PCIBIOS_MAX_MEM_32 is a 64-bit -1, so the following
> attempt to avoid putting a 32-bit BAR above 4G only works on x86,
> where PCIBIOS_MAX_MEM_32 is 0xffffffff.
>
> /* don't allocate too high if the pref mem doesn't support 64bit*/
> if (!(res->flags & IORESOURCE_MEM_64))
> max = PCIBIOS_MAX_MEM_32;
>
> I think we should fix this with a separate patch that removes
> PCIBIOS_MAX_MEM_32 altogether, replacing this use with an explicit
> 0xffffffff (or some other "max 32-bit value" symbol). I don't think
> there's anything arch-specific about this.
>
> So I'd like to see two patches here:
> 1) Avoid allocating 64-bit regions for 32-bit BARs
> 2) Try to allocate regions above 4GB for 64-bit BARs
>

Do we also need to track the maximum address available to the CPU?

-hpa