[Qemu-devel] Re: [PATCH V6 13/32] pci_host: consolidate pci config address access.

[Aurelien Jarno]

On Wed, Nov 04, 2009 at 03:14:26PM +0900, Isaku Yamahata wrote:
> On Tue, Nov 03, 2009 at 03:45:12PM +0200, Michael S. Tsirkin wrote:
> > > --- a/hw/pci_host.c
> > > +++ b/hw/pci_host.c
> > > @@ -32,6 +32,114 @@ do { printf("pci_host_data: " fmt , ## __VA_ARGS__); 
> > > } while (0)
> > >  #define PCI_DPRINTF(fmt, ...)
> > >  #endif
> > >  
> > > +static void pci_host_config_writel(void *opaque, target_phys_addr_t addr,
> > > +                                   uint32_t val)
> > > +{
> > > +    PCIHostState *s = opaque;
> > > +
> > > +#ifdef TARGET_WORDS_BIGENDIAN
> > > +    val = bswap32(val);
> > > +#endif
> > 
> > I know you just copied it, but isn't this just
> >     val = le32_to_cpu(val);
> > 
> > ?
> 
> Makes sense.
 
The original code is actually wrong, but le32_to_cpu(val), will break on
big endian hosts.

The fact is that QEMU doesn't emulate byteswap on buses. Hopefully on all
big endian machines we emulate, the PCI bus is always connected backward,
so we can simply do the byteswap depending on TARGET_WORDS_BIGENDIAN.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net