> On 11/29/2010 12:34 PM, Bjorn Helgaas wrote:
> > On Monday, November 29, 2010 11:30:09 am Bjorn Helgaas wrote:
> >>
> >> The last 1M before 4G contains the processor restart vector and usually
> >> the system ROM. We don't know the actual ROM size; I chose 1M because
> >> that's how much Windows 7 appears to avoid.
> >>
> >> Without this check, we can allocate PCI space that will never work. On
> >> Matthew's HP 2530p, we put the Intel GTT "Flush Page" at the very last
> >> page, which causes a spontaneous power-off:
> >>
> >> pci_root PNP0A08:00: host bridge window [mem 0xfee01000-0xffffffff]
> >> fffff000-ffffffff : Intel Flush Page (assigned by intel-gtt)
> >>
> >> Reference:
https://bugzilla.kernel.org/show_bug.cgi?id=23542
> >> Reported-by: Matthew Garrett <mjg@redhat.com>
> >> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
> >> ---
> >>
> >> arch/x86/include/asm/e820.h | 3 +++
> >> arch/x86/pci/i386.c | 10 +++++++++-
> >> 2 files changed, 12 insertions(+), 1 deletions(-)
> >>
> >>
> >> diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
> >> index 5be1542..c1e908f 100644
> >> --- a/arch/x86/include/asm/e820.h
> >> +++ b/arch/x86/include/asm/e820.h
> >> @@ -72,6 +72,9 @@ struct e820map {
> >> #define BIOS_BEGIN 0x000a0000
> >> #define BIOS_END 0x00100000
> >>
> >> +#define BIOS_ROM_BASE 0xfff00000
> >> +#define BIOS_ROM_END 0x100000000ULL
> >
> > I'm really not thrilled about hard-coding these addresses, so I'd
> > love it if somebody could suggest a way to discover them from the
> > BIOS.
> >
> > The E820 map doesn't reserve the last page:
> >
> > BIOS-e820: 00000000fed1c000 - 00000000fed20000 (reserved)
> > BIOS-e820: 00000000fffa0000 - 00000000fffa7000 (reserved)
> >
> > and I don't think there's any ACPI device that does either.
