Re: [Qemu-devel] [PATCH] sparc64 replace tsptr with helper routine

[Blue Swirl <blauwirbel@gmail.com>]

On Mon, Jul 20, 2009 at 10:00 PM, Igor
Kovalenko<igor.v.kovalenko@gmail.com> wrote:
> On Mon, Jul 20, 2009 at 10:49 AM, Blue Swirl<blauwirbel@gmail.com> wrote:
>> On Mon, Jul 20, 2009 at 12:19 AM, Igor
>> Kovalenko<igor.v.kovalenko@gmail.com> wrote:
>>> tl and tsptr of members sparc64 cpu state must be changed
>>> simultaneously to keep trap state window in sync with current
>>> trap level. Currently translation of store to tl does not change
>>> tsptr, which leads to corrupt trap state on corresponding
>>> trap level.
>>>
>>> This patch removes tsptr from sparc64 cpu state and replaces
>>> all uses with call to helper routine.
>>
>> I'd rather have the stores to TL fixed instead of introducing a
>> helper. A new function to set both TL and tsptr may help. Which stores
>> to TL do not change tsptr?
> The problem is with translate.c portion about handling wrpr
> (it sets tl only). My idea is that even remote possibility of tsptr
> and tl going out of sync guarantees killing one of them. Since
> tl is a real register I decided to loose tsptr.

Getting rid of env->tsptr is OK, but it seems pointless to introduce a
helper for such a small task. We could easily perform the get_tsptr
calculation at translation time.

>> On CPU reset, TL should be MAXTL for POR and MIN(TL+1, MAXTL) in other
>> cases but your patch would set it to 0.
>
> Right but please see that original code did not done that either :)
>
> Please see updated patch which additionally sets tl=maxtl.
> I decided to populate trap level, trap type and pstate with
> power-on reset values since other reset types are not handled yet.

Well, there is a kludge to handle the different PC for POR and others
in sun4u.c. Maybe this should be moved to helper.c and handled
properly with other reset type changes.