On Sunday 26 December 2021 23:20:27 Pali Rohár wrote:
> On Sunday 26 December 2021 23:13:11 Martin Mareš wrote:
> > Hi!
> >
> > > + else if (i < 7+6+4)
> > > + {
> > > + /*
> > > + * If kernel was compiled without CONFIG_PCI_IOV option then after
> > > + * the ROM line for configured bridge device (that which had set
> > > + * subordinary bus number to non-zero value) are four additional lines
> > > + * which describe resources behind bridge. For PCI-to-PCI bridges they
> > > + * are: IO, MEM, PREFMEM and empty. For CardBus bridges they are: IO0,
> > > + * IO1, MEM0 and MEM1. For unconfigured bridges and other devices
> > > + * there is no additional line after the ROM line. If kernel was
> > > + * compiled with CONFIG_PCI_IOV option then after the ROM line and
> > > + * before the first bridge resource line are six additional lines
> > > + * which describe IOV resources. Read all remaining lines in resource
> > > + * file and based on the number of remaining lines (0, 4, 6, 10) parse
> > > + * resources behind bridge.
> > > + */
> > > + lines[i-7].flags = flags;
> > > + lines[i-7].base_addr = start;
> > > + lines[i-7].size = size;
> > > + }
> > > + }
> > > + if (i == 7+4 || i == 7+6+4)
> >
> > This looks crazy: is there any other way how to tell what the bridge entries mean?
> > Checking the number of entries looks very brittle.
>
> I do not know any other way. Just for reference, here is a link to the
> function resource_show() and DEVICE_COUNT_RESOURCE enum:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pci-sysfs.c?h=v5.15#n136
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/pci.h?h=v5.15#n94
I have also checked flags and there is no indication if resource is
assigned on bridge as BAR or is forwarded behind the bridge.
Bjorn, Krzysztof: any idea if something better than checking number of
entries in "resource" node can be used to determinate type of entry at
specified line in "resource" node?
