On Thu, Jul 23, 2020 at 2:00 AM Richard Henderson <
richard.hender...@linaro.org> wrote:
> On 7/22/20 2:15 AM, frank.ch...@sifive.com wrote:
> > -static void vext_clear(void *tail, uint32_t cnt, uint32_t tot)
> > +static void vext_clear(void *tail, uint32_t vta, uint32_t cnt, uint32_t
> tot)
> > {
> > + if (vta == 0) {
> > + /* tail element undisturbed */
> > + return;
> > + }
> > +
> > /*
> > + * Tail element agnostic.
> > * Split the remaining range to two parts.
> > * The first part is in the last uint64_t unit.
> > * The second part start from the next uint64_t unit.
> > @@ -152,41 +168,50 @@ static void vext_clear(void *tail, uint32_t cnt,
> uint32_t tot)
> > if (cnt % 8) {
> > part1 = 8 - (cnt % 8);
> > part2 = tot - cnt - part1;
> > - memset((void *)((uintptr_t)tail & ~(7ULL)), 0, part1);
> > - memset((void *)(((uintptr_t)tail + 8) & ~(7ULL)), 0, part2);
> > + memset((void *)((uintptr_t)tail & ~(7ULL)), 1, part1);
> > + memset((void *)(((uintptr_t)tail + 8) & ~(7ULL)), 1, part2);
> > } else {
> > - memset(tail, 0, part2);
> > + memset(tail, 1, part2);
> > }
> > }
>
> "1s" surely means all bits set to 1, not each byte to 1.
>
You're correct, I can't just simply replace the value from 0 to 1.
>
> Is there any reason to do anything with VTA/VMA at all? One alternative
> for
> "agnostic" is to leave the values undisturbed. So the quickest thing for
> qemu
> to do is remove all of this code. Then we don't have to pass the values in
> translate either.
>
> Which is exactly what is recommended in the 4th paragraph of the notes
> following the VTA/VMA description.
>
>
I was trying to keep these codes as an option for the user to specify the
behaviors of VTA.
But as long as it's easier for QEMU to just treat VTA/VMA as agnostic(no
changes)/undisturbed.
I will remove all the clean functions in my next patchset.
>
> r~
>
Frank Chang
