[SeaBIOS] [PATCH] map 64-bit PCI BARs at location provided by emulator
imammedo at redhat.com
Fri Oct 11 15:53:02 CEST 2013
On Fri, 11 Oct 2013 14:35:50 +0200
Gerd Hoffmann <kraxel at redhat.com> wrote:
> On Fr, 2013-10-11 at 12:19 +0200, Igor Mammedov wrote:
> > Currently 64-bit PCI BARs are unconditionally mapped by BIOS right
> > over 4G + RamSizeOver4G location, which doesn't allow to reserve
> > extra space before 64-bit PCI window. For memory hotplug an extra
> > RAM space might be reserved after present 64-bit RAM end and BIOS
> > should map 64-bit PCI BARs after it.
> > Introduce "etc/pcimem64-start" romfile to provide BIOS a hint
> > where it should start mapping of 64-bit PCI BARs. If romfile is
> > missing BIOS reverts to legacy behavior and starts mapping right
> > after high memory.
> Looks good overall.
> > struct pci_region r64_mem, r64_pref;
> > + u64 base64 = le64_to_cpu(romfile_loadint("etc/pcimem64-start",
> > + 0x100000000ULL + RamSizeOver4G));
> Should we sanity-check base64 maybe?
> Make sure it isn't smaller than 0x100000000ULL + RamSizeOver4G?
If it would be less than 0x100000000ULL + RamSizeOver4G then it would mean
that QEMU for some reason decided to overshadow present RAM with PCI hole.
It would add a couple of extra bytes to BIOS and point where it should fail
or at least print a warning that nobody will read at runtime.
I think it's better to assert on QEMU side and abort even before guest
started if it's considered as error.
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