From: Yuli Barcohen <yuli@arabellasw.com>
To: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Cc: Joakim Tjernlund <joakim.tjernlund@lumentis.se>,
Jason McMullan <jason.mcmullan@gmail.com>,
linux-ppc-embedded <linuxppc-embedded@ozlabs.org>
Subject: Re: mpc8xx and ld.so problem
Date: Sun, 10 Jul 2005 10:31:55 +0300 [thread overview]
Message-ID: <17104.52971.2458.935609@astp0002.localdomain> (raw)
In-Reply-To: <20050708003639.GA5174@dmt.cnet>
>>>>> Marcelo Tosatti writes:
Yuli> [...deleted...]
Jason> Ha. Funny. The glibc powerpc maintainer doesn't want any
Jason> embedded fixes in the mainline. Last I checked, that was for
Jason> 'the tools vendors' to fix.
Jason> "We won't work around processor bugs" is their philosophy.
Yuli> [...deleted...]
Yuli> I investigated the problem a bit when I had trouble with a
Yuli> self-compiled glibc a year or so ago. IIRC, I found bug in the
Yuli> memset code, not in the chip. The code was just wrong for
Yuli> cache line sizes not equal to 32. So memset.S is good for 60x
Yuli> series (PQII included) but for 8xx it fails.
Marcelo> I suppose you didnt actually use dcbz for userspace memset
Marcelo> on 8xx?
Standard glibc did. After the fix, it doesn't do it any more on our
systems.
Yuli> We use dcbX instructions in some kernel drivers and since we
Yuli> never had any problems with those drivers I'm a bit surprised
Yuli> to hear that all 8xx chips have got that bug.
Marcelo> The problem is that the DAR register is correctly unset (it
Marcelo> comes as NULL IIRC) on pagefaults for the dcbz
Marcelo> instruction. The dcbz instructions you issue are probably
Marcelo> always works on kernel addresses whose pagetables are
Marcelo> present?
It's not dcbz, it's dcbi/dcbf. And yes, they work on kernel addresses. I
never investigated if the page tables are present or not because there
were no problems.
Marcelo> Joakim has developed a workaround for the
Marcelo> problem... although I promised him several times to test it
Marcelo> I never managed to get dcbz to work on the kernel copying
Marcelo> functions. :(
[...patch deleted...]
Well, if I manage to find time, I'll try it. No timetables though. I'm
not sure if using dcbz in user-space memset is such a great
optimisation. It well can be an example of over-engineering.
--
========================================================================
Yuli Barcohen | Phone +972-9-765-1788 | Software Project Leader
yuli@arabellasw.com | Fax +972-9-765-7494 | Arabella Software, Israel
========================================================================
next prev parent reply other threads:[~2005-07-10 7:32 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <42C1AAC1.4060702@gmail.com>
[not found] ` <20050629085913.GA2153@logos.cnet>
[not found] ` <faba7798050630071347d4ad63@mail.gmail.com>
2005-07-01 9:44 ` mpc8xx and ld.so problem Marcelo Tosatti
2005-07-01 14:55 ` Jason McMullan
2005-07-01 10:17 ` Marcelo Tosatti
2005-07-01 18:56 ` Jason McMullan
2005-07-01 14:42 ` Marcelo Tosatti
2005-07-04 8:22 ` Yuli Barcohen
2005-07-05 19:53 ` Tom Rini
2005-07-06 8:58 ` Yuli Barcohen
2005-07-08 0:36 ` Marcelo Tosatti
2005-07-10 7:31 ` Yuli Barcohen [this message]
2005-07-13 15:41 ` Theo Gjaltema
2005-07-13 20:32 ` Wolfgang Denk
2005-07-13 21:32 ` Theo Gjaltema
2005-07-13 23:11 ` Wolfgang Denk
2005-07-14 5:44 ` Anton Wöllert
2005-07-14 8:23 ` ptrace on linux 2.6.12 causes oops Anton Wöllert
2005-07-14 13:31 ` Kumar Gala
2005-07-14 11:20 ` Marcelo Tosatti
[not found] ` <faba77980507140809ad923db@mail.gmail.com>
2005-07-14 15:11 ` Anton Wöllert
2005-07-14 20:27 ` aris
2005-07-14 11:19 ` Marcelo Tosatti
2005-07-15 9:42 ` Anton Wöllert
2005-07-15 5:03 ` Marcelo Tosatti
2005-07-03 16:01 ` mpc8xx and ld.so problem Anton Wöllert
2005-07-01 18:40 Tjernlund
-- strict thread matches above, loose matches on Subject: below --
2005-07-14 13:32 Joakim Tjernlund
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