[Xen-devel] Re: pciback_field_is_dup needs a fix

[Jambunathan K <jambunathan@xxxxxxxxxx>]

Here is quick log from frontend debug showing this happening:

pciback 0000:0b:00.3: added config field at offset 0x04
pciback 0000:0b:00.3: added config field at offset 0x3c
pciback 0000:0b:00.3: added config field at offset 0x3d
pciback 0000:0b:00.3: added config field at offset 0x0c
pciback 0000:0b:00.3: added config field at offset 0x0d
pciback 0000:0b:00.3: added config field at offset 0x0f
pciback 0000:0b:00.3: added config field at offset 0x10
pciback 0000:0b:00.3: added config field at offset 0x14
pciback 0000:0b:00.3: added config field at offset 0x18
pciback 0000:0b:00.3: added config field at offset 0x1c
pciback 0000:0b:00.3: added config field at offset 0x20
pciback 0000:0b:00.3: added config field at offset 0x24
pciback 0000:0b:00.3: added config field at offset 0x30

pciback 0000:0b:00.3: Found capability 0x1 at 0x80

pciback 0000:0b:00.3: added config field at offset 0x80
pciback 0000:0b:00.3: added config field at offset 0x82
                                                                  
<------ 0x80 + 4 missing here
pciback 0000:0b:00.3: added config field at offset 0x86
pciback 0000:0b:00.3: added config field at offset 0x87

Thanks,
Jambunathan K.


Jambunathan K wrote:
> Shouldn't pciback_field_is_dup(dev, field->offset) be scoped to 
> include the base_offset as well?
> Currently with xen-3.0.4 the issue is this:
>
> Adding of  PCI_PM_CTRL (at offset 4)  to the 'config_fields list' gets 
> skipped because it ends up being a duplicate of PCI_COMMAND (at offset 
> 4 as well).  As a result when a PCI device behind a PCI frontend does 
> a power up using pci_enable_device() the following message gets 
> flashed on the console.
> pciback 0000:0b:00.3: Driver tried to write to a read-only 
> configuration space field at offset 0x84, size 2. This may be 
> harmless, but if you have problems with your device:
> 1) see permissive attribute in sysfs
> 2) report problems to the xen-devel mailing list along with details of 
> your device obtained from lspci.
> Thanks,
> Jambunathan K.
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