Re: [Qemu-devel] [PATCH 12/19] hw/isa: Declare device little or big endian

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 8/26/19 4:21 PM, Tony Nguyen wrote:
> For each device declared with DEVICE_NATIVE_ENDIAN, find the set of
> targets from the set of target/hw/*/device.o.
> 
> If the set of targets are all little or all big endian, re-declare
> as DEVICE_LITTLE_ENDIAN or DEVICE_BIG_ENDIAN respectively.
> 
> Then, on inspection:
> - if not used, re-declare as DEVICE_HOST_ENDIAN.
> - if max/min size=1, re-declare as DEVICE_HOST_ENDIAN.

Here you say DEVICE_HOST_ENDIAN,

> - if just a bit bucket, re-declare as DEVICE_HOST_ENDIAN
> - if PCI, re-declare as DEVICE_LITTLE_ENDIAN.
> - if for {ARM|unicore32} only, re-declare as DEVICE_LITTLE_ENDIAN.
> - if for SPARC only, re-declare as DEVICE_BIG_ENDIAN.
> 
> Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
> ---
>   hw/isa/vt82c686.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
> index 50bd28fa82..400f2b3c87 100644
> --- a/hw/isa/vt82c686.c
> +++ b/hw/isa/vt82c686.c
> @@ -109,7 +109,7 @@ static uint64_t superio_ioport_readb(void *opaque, hwaddr addr, unsigned size)
>   static const MemoryRegionOps superio_ops = {
>       .read = superio_ioport_readb,
>       .write = superio_ioport_writeb,
> -    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .endianness = DEVICE_LITTLE_ENDIAN,

But here you use DEVICE_LITTLE_ENDIAN.

For 8-bit I/O port endianess doesn't matter, so I'm not sure what is the 
correct choice. Can we simply remove the .endianness line, since the 
won't be ever used?

>       .impl = {
>           .min_access_size = 1,
>           .max_access_size = 1,
>