From: Marcelo Tosatti <marcelo.tosatti@cyclades•com>
To: Dan Malek <dan@embeddededge•com>
Cc: Joakim Tjernlund <Joakim.Tjernlund@lumentis•se>,
linuxppc-embedded@ozlabs•org
Subject: Re: 8xx v2.6 TLB problems and suggested workaround
Date: Fri, 8 Apr 2005 08:07:25 -0300 [thread overview]
Message-ID: <20050408110724.GG19449@logos.cnet> (raw)
In-Reply-To: <19116173cb07648317c2a73a9c822c70@embeddededge.com>
Hi Dan,
On Thu, Apr 07, 2005 at 10:09:58PM -0400, Dan Malek wrote:
>
> On Apr 7, 2005, at 3:38 PM, Marcelo Tosatti wrote:
>
> >Would be nice to have someone from 8xx team look into this?
>
> I'll look into it and find some solution.
What do you envision as another solution?
We have two now:
1) _tlbie() on update_mmu_cache() surrounded by CONFIG_8xx #ifdef
Did you give up about it?
2) jump directly from DataTLBMiss to fault handler.
You seem to dislike it.
What else you think can be done?
> I suspect it is an interaction with the previous TLB miss and the behavior
> of the dcbst TLB look up. Perhaps, if we ensure the
> TLB entry is not valid at the time of the dcbst, it will work.
Note that the TLB entry is _not valid_ at the time of the dcbst:
BDI>rds 824
SPR 824 : 0x10011f05 268508933
BDI>rds 825
SPR 825 : 0x000001e0 480
BDI>rds 826
SPR 826 : 0x00001f00 7936
bit 18 (valid bit) of SPR 826 is not set.
So even with the TLB invalid, dcbst misbehaves.
> This is why the tlbie() I added as a hack a long time
> ago made the "problem" disappear. The other dcbxx
> instructions in the code work on already existing pages,
> while this one is a special case of a miss on a page
> that doesn't exist.
>
> Thanks.
>
> -- Dan
next prev parent reply other threads:[~2005-04-08 23:28 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-05 21:51 8xx v2.6 TLB problems and suggested workaround Joakim Tjernlund
2005-04-06 12:16 ` Marcelo Tosatti
2005-04-06 21:24 ` Joakim Tjernlund
2005-04-07 12:00 ` Marcelo Tosatti
2005-04-07 20:35 ` Joakim Tjernlund
2005-04-07 19:38 ` Marcelo Tosatti
2005-04-08 2:09 ` Dan Malek
2005-04-08 11:07 ` Marcelo Tosatti [this message]
2005-04-09 5:16 ` Dan Malek
2005-04-09 19:03 ` Joakim Tjernlund
2005-04-09 22:37 ` Marcelo Tosatti
2005-04-10 10:08 ` Joakim Tjernlund
2005-04-22 17:14 ` Marcelo Tosatti
2005-04-23 21:55 ` Dan Malek
2005-04-23 22:07 ` Joakim Tjernlund
2005-04-23 22:23 ` Dan Malek
2005-04-08 8:01 ` Joakim Tjernlund
2005-04-08 13:39 ` Dan Malek
2005-04-08 14:29 ` Joakim Tjernlund
-- strict thread matches above, loose matches on Subject: below --
2005-04-04 19:17 Marcelo Tosatti
2005-04-04 20:09 ` Marcelo Tosatti
2005-04-05 7:08 ` Pantelis Antoniou
2005-04-05 1:11 ` Kumar Gala
2005-04-05 15:58 ` Dan Malek
2005-04-05 11:41 ` Marcelo Tosatti
2005-04-05 20:26 ` Marcelo Tosatti
2005-04-06 6:00 ` Pantelis Antoniou
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