Philippe Mathieu-Daudé <[email protected]> 于2019年4月21日周日 下午6:28写道：
> Hi Li,
>
> The patch title is not very descriptive, maybe "allow 64-bit access"
>
>
> On 4/20/19 6:14 PM, Li Qiang wrote:
> > The edu spec said, the MMIO area can be accessed by 8 bytes.
>
> or 64-bit...
>
> > However currently the 'max_access_size' is not so the MMIO
> > access dispatch can only access 4 bytes one time. This patch
>
> 32-bit
>
> > fixes this to respect the spec.
> >
> > Notice: here the 'min_access_size' is not a must, I set this
> > for completement.
>
> Which one? valid/impl? I think you can drop this comment from the commit
> description.
>
>
Both needed. from memory_access_size, if we has no valid.max_access_size,
this function will set it to 4.
static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr)
{
unsigned access_size_max = mr->ops->valid.max_access_size;
/* Regions are assumed to support 1-4 byte accesses unless
otherwise specified. */
if (access_size_max == 0) {
access_size_max = 4;
}
...
}
>From access_with_adjusted_size, if we has no impl.max_access_size,
this function will set it to 4.
ps: I will appreciate if anyone can explain what's the meaning of valid and
impl's min/max_access_size
and how it affects the behavior.
Thanks,
Li Qiang
>
> > Signed-off-by: Li Qiang <[email protected]>
> > ---
> > hw/misc/edu.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/hw/misc/edu.c b/hw/misc/edu.c
> > index 91af452c9e..65fc32b928 100644
> > --- a/hw/misc/edu.c
> > +++ b/hw/misc/edu.c
> > @@ -289,6 +289,15 @@ static const MemoryRegionOps edu_mmio_ops = {
> > .read = edu_mmio_read,
> > .write = edu_mmio_write,
> > .endianness = DEVICE_NATIVE_ENDIAN,
> > + .valid = {
> > + .min_access_size = 4,
>
> Per the spec, this is correct.
>
> > + .max_access_size = 8,
>
> Correct.
>
> > + },
> > + .impl = {
> > + .min_access_size = 4,
>
> OK.
>
> > + .max_access_size = 8,
>
> Correct.
>
> > + },
> > +
> > };
> >
> > /*
> >
>
> With title/description updated:
> Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
>
>
