[OpenBIOS] sparc64's get_physical_address_code should not fault on TTE's with V=0

[Blue Swirl]

On 1/13/09, Jakub Jermar <jakub at jermar.eu> wrote:
> Blue Swirl wrote:
>  > On 1/12/09, Jakub Jermar <jakub at jermar.eu> wrote:
>  >> Hi,
>  >>
>  >>  when I make the following change to helper.c, get_physical_address_code:
>  >>
>  >>  -        // ctx match, vaddr match?
>  >>  +        // ctx match, vaddr match, valid?
>  >>          if (env->dmmuregs[1] == (env->itlb_tag[i] & 0x1fff) &&
>  >>  -            (address & mask) == (env->itlb_tag[i] & ~0x1fffULL)) {
>  >>  -            // valid, access ok?
>  >>  -            if ((env->itlb_tte[i] & 0x8000000000000000ULL) == 0 ||
>  >>  -                ((env->itlb_tte[i] & 0x4) && is_user)) {
>  >>  +            (address & mask) == (env->itlb_tag[i] & ~0x1fffULL) &&
>  >>  +            env->itlb_tte[i] & 0x8000000000000000ULL) {
>  >>  +            // access ok?
>  >>  +            if ((env->itlb_tte[i] & 0x4) && is_user) {
>  >>
>  >>  HelenOS gets a little bit further than without this change and seems
>  >>  to panic more or less gracefully later.
>  >>
>  >>  In short, non-valid entries should be skipped by the loop in
>  >>  get_physical_address_code instead of causing TFAULT, because
>  >>  the ITLB can contain a valid entry for the same address. The
>  >>  same is true for DTLB.
>  >>
>  >>  Can you confirm this?
>  >
>  > Yes, this looks correct. I'll apply a fix.
>
>
> Thanks!
>
>  With this fix in place, HelenOS most of the time panics on:
>
>  Kernel panic: Cannot find property 'screen'.
>
>  I.e. it searches property 'screen' in /aliases and doesn't
>  find any. If it is not there already, could you please add
>  it (together with keyboard) to openbios?

Recent OpenBIOS (including the version in Qemu) should have both
"screen" and "keyboard" aliases. In /chosen there is "display" (?) and
"keyboard".