On Wed, Jun 08, 2016 at 01:59:59PM +0200, Andrew Jones wrote:
> > > So you need 5 functions
> > >
> > > uint32_t get_mask(int bar)
> > > {
> > > ...
> > > }
> > >
> > > uint32_t read_dance(int bar)
> > > {
> > > read-write1s-dance
> > > return readl
> > > }
> > >
> > > uint32_t get_size32(int bar)
> > > {
> > > uint32_t size = read_dance(bar) & get_mask(bar);
> > > return ~size + 1;
> > > }
> > >
> > > uint64_t get_size64(int bar)
> > > {
> > > uint64_t size = read_dance(bar) & get_mask(bar);
> > > uint64_t size_hi = read_dance(bar + 1);
> > >
> > > size |= size_hi << 32;
> > > return ~size + 1;
> > > }
> > >
> > > uint64_t get_size(int bar)
> > > {
> > > return bar_size(bar) == BAR64 ? get_size64(bar) : get_size32(bar);
> > > }
> >
> > If the above is a pseudo code or you want me to rework using these
> > functions?
>
> Yes and no. You can do what you like, but pci_bar_size32 should
> return a size (like my get_size32), not a 2's complement of size,
> otherwise the name is wrong.
Right. So my pci_bar_size32 is your read_dance. Want to use that name
or i.e. pci_bar_size_complement?
> > If not, below is how it could look like.
> >
> > Also, looking at your get_size() I noticed a bug in my version :-)
> > when read_dance() is followed by readl() returns zero - that means no
> > (more) BAR(s).
> >
> > phys_addr_t pci_bar_size(pcidevaddr_t dev, int bar_num)
> > {
> > uint32_t size;
> > uint32_t bar;
> >
> > size = pci_bar_size32(dev, bar_num);
> > if (!size)
> > return 0;
>
> Should callers ever call pci_bar_size on a bar_num that will result
> in zero, "no more BARs"? If not, then you can assert here. Otherwise
> will all callers know what zero means, and check for it?
Yes, it is an indication a BAR is implemented in HW. But I misled you :/
I remember some code stopped on a zero-sized BAR, but I do not recall
what code it was. There is nothing in specs about stopping and both
Seabios and Linux just continue probing. So I will update the breaks to
continues.
> Thanks,
> drew
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
