Re: [PATCH 00/15] Backport 8xx TLB to 2.4

Willy Tarreau [off-list ref] wrote on 2011/06/14 21:31:06:

Hi Joakim,

On Tue, Jun 14, 2011 at 03:54:45PM +0200, Joakim Tjernlund wrote:

quoted

This is a backport from 2.6 which I did to overcome 8xx CPU
bugs. 8xx does not update the DAR register when taking a TLB
error caused by dcbX and icbi insns which makes it very
tricky to use these insns. Also the dcbst wrongly sets the
the store bit when faulting into DTLB error.
A few more bugs very found during development.

I know 2.4 is in strict maintenance mode and 8xx is obsolete
but as it is still in use I wanted 8xx to age with grace.

OK, I'm not opposed to merge these patches and I really welcome your
work and want to thank you for having done it. However, I have
absolutely *zero* skills on ppc, so I want to ensure that someone
(possibly you) will be able to back me up in case of reported
regressions once these patches are merged. Since you say that the
code works on your board, I'm not much worried but at least Dan's
comment about the risk of performance regression has to be considered.
If we all agree that it's a tradeoff between performance and stability
or security, then that's a different matter of course !

Yes, I will still be here :) If there are any regressions I will help out. If
we can't fix it, we can easily back these changes out. I guess I and
Dan will come to some agreement soon and I will post additional, if needed,
patches on top of what I already sent once Dan is happy.

 Jocke