Re: [Xen-devel] [RFC][PATCH 12/13] hvmloader/pci: skip reserved ranges

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2015/5/15 15:44, Jan Beulich wrote:
> > > > On 15.05.15 at 09:34, <tiejun.chen@xxxxxxxxx> wrote:
> > So I think we may need to adjust pci_mem_start like this,
> >
> > @@ -301,6 +301,19 @@ void pci_setup(void)
> >                pci_mem_start <<= 1;
> >        }
> >
> > +    /* Relocate PCI memory that overlaps reserved space, like RDM. */
> > +    for ( j = 0; j < memory_map.nr_map ; j++ )
> > +    {
> > +        if ( memory_map.map[j].type != E820_RAM )
> > +        {
> > +            reserved_end = memory_map.map[j].addr + memory_map.map[j].size;
> > +            if ( check_overlap(pci_mem_start, pci_mem_end,
> > +                               memory_map.map[j].addr,
> > +                               memory_map.map[j].size) )
> > +                pci_mem_start -= memory_map.map[j].size >> PAGE_SHIFT;
> > +        }
> > +    }
> > +
> >        if ( mmio_total > (pci_mem_end - pci_mem_start) )
> >        {
> >            printf("Low MMIO hole not large enough for all devices,"
> >
> > Right?
> I think that gets you in the right direction, but isn't enough, as it
> doesn't account for (unavoidable) gaps (BARs are always a power
> of 2 in size and accordingly aligned).
Right.

But as you see, we always take this action, >> PAGE_SHIFT, so this means 
its always a sort of power of 2.
Additionally, lets go back here,

        if ( (base < resource->base) || (base > resource->max) )
        {
            printf("pci dev %02x:%x bar %02x size "PRIllx": no space for "
                   "resource!\n", devfn>>3, devfn&7, bar_reg,
                   PRIllx_arg(bar_sz));
            continue;
        }

I mean even without rdm, the original codes don't consider handling this 
lack of space from a alignment in advance, right?

Thanks
Tiejun

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