Re: [Xen-devel] [PATCH 3/3] passthrough: allow to suppress SERR and PERR signaling altogether

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.04.14 at 14:47, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 03/04/14 10:41, Jan Beulich wrote:
>> +        if ( val & PCI_STATUS_CHECK )
>> +        {
>> +            printk(XENLOG_INFO "%04x:%02x:%02x.%u status %04x\n",
>> +                   seg, bus, dev, func, val);
> 
> What is the purpose of this printk?  From the text alone it is not obvious.

It's simply to have an indication that the status register was written
(and that certain bits may have got cleared).

>> +            pci_conf_write16(seg, bus, dev, func, PCI_STATUS, val);
> 
> I dont think this code has any right to clear status bits other than the
> ones it is checking for, so the write should be "val & PCI_STATUS_CHECK"

Hmm, the intention is to clear all status fields that can be cleared, and
the if() around the write is just to avoid the printk() and the write if
possible. PCI_STATUS_CHECK already includes all changeable bits, and
I'd expect any of the few that are currently reserved to get added
here, should they attain a meaning of a writable one.

Jan


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