Re: [PATCH] x86/pci: make pci_mem_start to be aligned only -v3

From: Jesse Barnes
Date: Thu Apr 16 2009 - 12:32:18 EST


On Tue, 14 Apr 2009 17:41:35 -0700
Yinghai Lu <yinghai@xxxxxxxxxx> wrote:

>
> Impact: make more big space below 4g for assigning to unassigned pci
> devices
>
> don't need to reserved one round after the gapstart.
>
> v2: Linus said: "
> We've definitely seen ACPI code or integrated graphics stuff
> that steals a lot of memory at the end, which means that
> end-of-RAM might be not at 2GB, but at 2GB-16MB-1MB, for example (1MB
> of "ACPI data", and 16MB of "stolen video ram").
>
> At a minimum, if we do this, I'd like to make sure we round
> up to a big boundary (eg 32MB or something - exactly because a
> missing 16MB can easily be some integrated stolen video memory).
>
> Sure, we do that whole
>
> while ((gapsize >> 4) > round)
> round += round;
>
> thing, so that if the gap is large, then we'll certainly get
> to 32MB too, but I think your patch matters the most exactly when the
> gap is small. Maybe we could just raise the initial minimum rounding
> from 1MB to 32MB? ...
> Alternatively, maybe we can make sure that we round up to at
> least X bytes from the end of RAM, and to at least Y bytes from the
> end of some RESERVED thing."
> v3: take pci_mem_start - low_top_ram bigger than half around, aka 16M
> at least

Any comments on this one, Linus? Should I include your ack?

Thanks,
--
Jesse Barnes, Intel Open Source Technology Center
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