Re: [Qemu-devel] Re: ACPI error when mapping a 2GB BAR w/ 4GB of RAM

[Cam Macdonell <cam@cs.ualberta.ca>]

On Fri, Sep 17, 2010 at 2:04 PM, Chris Wright <chrisw@redhat.com> wrote:
> * Cam Macdonell (cam@cs.ualberta.ca) wrote:
>> After fixing the resource_size_t return value with
>> pci_resource_alignment, I see one other strange behaviour only when
>> using 4GB of RAM and a 2GB BAR.  I haven't found any other combination
>> of RAM/BAR size that triggers this bug.  I am using 2.6.36-rc3.
>>
>> ACPI Error: The DSDT has been corrupted or replaced - old, new headers
>> below (20100702/tbutils-372)
>> ACPI: DSDT (null) 01F15 (v01   BXPC   BXDSDT 00000001 INTL 20090123)
>> ACPI:      (null) 00000 (v00                 00000000      00000000)
>> ACPI Error: Please send DMI info to linux-acpi@vger.kernel.org
>> If system does not work as expected, please boot with acpi=copy_dsdt
>> (20100702/tbutils-378)
>> ACPI: PCI Interrupt Link [LNKC] disabled and referenced, BIOS bug
>> ACPI Exception: AE_AML_INVALID_RESOURCE_TYPE, Evaluating _CRS
>> (20100702/pci_link-283)
>> ACPI: Unable to set IRQ for PCI Interrupt Link [LNKC]. Try pci=noacpi
>> or acpi=off
>> virtio-pci 0000:00:03.0: PCI INT A: no GSI - using ISA IRQ 11
>> Non-volatile memory driver v1.3
>> Linux agpgart interface v0.103
>> Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
>
> IIRC,  the pci hole is only 1.5G in the BIOS, can you verify that
> seabios is doing the right thing?

I'm not sure what the right thing for seabios to do is.  Here is the
seabios output related to the device.

PCI: bus=0 devfn=0x20: vendor_id=0x1af4 device_id=0x1110
region 0: 0xf2040000
init smm
init boot device ordering

<snip>

Attempting to init PCI bdf 00:04.0 (vd 1af4:1110)
Attempting to map option rom on dev 00:04.0
Option rom sizing returned 0 0
Checking rom 0x000c9800 (sig aa55 size 17)
Checking rom 0x000cc000 (sig aa55 size 2)
Checking rom 0x000c9000 (sig aa55 size 4)
Checking rom 0x000c9800 (sig aa55 size 17)
Checking rom 0x000cc000 (sig aa55 size 2)
Mapping hd drive 0x000fdb50 to 0
Running option rom at c980:0003
Running option rom at cc00:0003
pmm_malloc zone=0x000f515c handle=ffffffff size=36 align=10
ret=0x000fdaf0 (detail=0x7ffefca0)
ebda moved from 9fc00 to 9f400
pmm_malloc zone=0x000f5154 handle=ffffffff size=2048 align=10
ret=0x0009f800 (detail=0x7ffefb40)
finalize PMM
malloc finalize

when using a BAR of 2GB or less, there is an additional write to the
PCI space of the device, which may be from the bios

pci_write_config: (val) 0xffffffff -> 0x18 (addr)
pci_read_config: (val) 0x80000004 <- 0x18 (addr)
pci_write_config: (val) 0x4 -> 0x18 (addr)
pci_write_config: (val) 0x3 -> 0x4 (addr)
pci_read_config: (val) 0x0 <- 0x1c (addr)
pci_write_config: (val) 0xffffffff -> 0x1c (addr)
IVSHMEM: guest pci addr = ffffffff00000000, guest h/w addr =
4312137728, size = 80000000

so is it succeeding with smaller sizes (> 2GB) because it fits in the
bios' pci hole?

Cam

>
> thanks,
> -chris
>
>