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Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI h
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug |
Date: |
Wed, 18 May 2016 18:06:45 +0300 |
On Wed, May 18, 2016 at 05:52:29PM +0300, Marcel Apfelbaum wrote:
> On 05/18/2016 05:42 PM, Michael S. Tsirkin wrote:
> >On Wed, May 18, 2016 at 04:31:46PM +0200, Igor Mammedov wrote:
> >>On Wed, 18 May 2016 17:12:09 +0300
> >>Marcel Apfelbaum <address@hidden> wrote:
> >>
> >>>On 05/18/2016 05:11 PM, Michael S. Tsirkin wrote:
> >>>>On Wed, May 18, 2016 at 03:59:29PM +0200, Igor Mammedov wrote:
> >>>>>On Sun, 15 May 2016 22:23:32 +0300
> >>>>>Marcel Apfelbaum <address@hidden> wrote:
> >>>>>
> >>>>>>Using the firmware assigned MMIO ranges for 64-bit PCI window
> >>>>>>leads to zero space for hot-plugging PCI devices over 4G.
> >>>>>>
> >>>>>>PC machines can use the whole CPU addressable range after
> >>>>>>the space reserved for memory-hotplug.
> >>>>>>
> >>>>>>Signed-off-by: Marcel Apfelbaum <address@hidden>
> >>>>>that patch also has side effect of unconditionally adding
> >>>>>QWordMemory() resource in PCI0._CRS
> >>>>>on all machine types with QEMU generated ACPI tables.
> >>>>>
> >>>>>Have you tested that it won't break boot of legacy OSes
> >>>>>(XP, WS2003, old linux with 32bit kernel)?
> >>>>
> >>>>It's almost sure it break it.
> >>>>Maybe you can check _REV in _CRS to work around this for XP.
> >>>
> >>>I'll try it.
> >>but only after you check if just presence of QWord would crash XP,
> >>so in case it doesn't crash we would keep _CRS simple static
> >>structure.
> >>
> >>I very vaguely recall that XP ignored QWord in PCI0._CRS,
> >>but it was long time ago so it won't hurt to recheck.
> >
> >I played with different guests (32 and 64 bit)
> >at some point.
> >
> >Generally, windows tends to crash when CRS resources exceed the
> >supported limits
> >of physical memory (sometimes with weird off by one errors,
> >e.g. win7 32 bit seems to survive with a 36 bit pci hole even though
> >this means the max address is 2^37-1 which it can't address).
> >
> >This might depend on CPU as well.
>
> It seems QEMU returns 40-bit as CPU addressable bits, but I might got it
> wrong.
>
> >
> >Which makes me ask: why don't we fix this in BIOS?
> >If you want it to allocate a large window, do it.
>
> I don't follow, BIOS can assign resources to PCI devices, but how to
> specify a MMIO range for hot-plug? Add it to the CRS of the host-bridge,
> right?
>
> Thanks,
> Marcel
>
> [...]
Ah I forgot on PC there's no register for this. On Q35 there is.
--
MST
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, (continued)
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Igor Mammedov, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Laszlo Ersek, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Marcel Apfelbaum, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Michael S. Tsirkin, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Marcel Apfelbaum, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Igor Mammedov, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Marcel Apfelbaum, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Michael S. Tsirkin, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Marcel Apfelbaum, 2016/05/18
- Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug,
Michael S. Tsirkin <=
Re: [Qemu-devel] [PATCH V2 2/4] pci: reserve 64 bit MMIO range for PCI hotplug, Michael S. Tsirkin, 2016/05/18
[Qemu-devel] [PATCH V2 1/4] hw/pc: extract reserved memory end computation to a standalone function, Marcel Apfelbaum, 2016/05/15
[Qemu-devel] [PATCH V2 3/4] acpi: refactor pxb crs computation, Marcel Apfelbaum, 2016/05/15
[Qemu-devel] [PATCH V2 4/4] hw/apci: handle 64-bit MMIO regions correctly, Marcel Apfelbaum, 2016/05/15