Hi,
> > static const uint32_t virtio_gpu_cursor_formats[] = {
> > +#ifdef __BIG_ENDIAN
> > + DRM_FORMAT_BGRA8888,
> > +#else
> > DRM_FORMAT_ARGB8888,
> > +#endif
>
> DRM formats are supposed to be little endian, so this isn't really
> correct.
Well, maybe they where *intended* to be little endian at some point in
the past. The actual code appears to interpret them as native endian
though.
Lets take a simple example, the bochs driver (qemu sdvga). It supports
32 bpp with depth 24 (DRM_FORMAT_XRGB8888) as the one and only
framebuffer format (see bochs_user_framebuffer_create). We still had to
add a special register to the virtual hardware so the guest can signal
to the host whenever the framebuffer is big endian or little endian (see
bochs_hw_init), so both ppc64 and ppc64le guests work properly with the
qemu stdvga.
So, bigendian guests assume that DRM_FORMAT_XRGB8888 is big endian not
little endian. And given that the fourcc codes are used in the
userspace/kernel API too (see DRM_IOCTL_MODE_ADDFB2) I think we can't
change that any more ...
cheers,
Gerd
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