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

Steven Newbury
2012-06-06T09:44:13Z

On Tue,  5 Jun 2012, 06:04:57 BST, Yinghai Lu <yinghai@kernel.org> wrote:
> > Linux has a long history of allocating bottom-up.  Windows has a long
> > history of allocating top-down.  You're proposing a third alternative,
> > allocating bottom-up starting at 4GB for 64-bit BARs.  If we change
> > this area, I would prefer something that follows Windows because I
> > think it will be closer to what's been tested by Windows.  Do you
> > think your alternative is better?
>
> hope we can figure out how windows is making it work.
>
> Steve, Can you check if Windows is working with your test case ?
>
> If it works, we may try do the same thing from Linux, so you will not
> need to append "pci=nocrs pci=alloc_high"...
>
Unfortunately I don't have a 64 bit version of Windows to test with. Vista(32 bit) fails to even boot when docked, hot-plugging fails to allocate resources, but at least doesn't crash.

>From what I've read about the (64 bit) Windows allocation stragegy it's closer to Yinghai's method than the Linux default, preferring 64 bit resources (>4G) when possible. I'll try to find the specification document again.