From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
Subject: Re: [PATCH] MIPS: DECstation HRT calibration bug fixes
Date: Tue, 17 Sep 2013 10:41:26 +0200 [thread overview]
Message-ID: <20130917084126.GA9785@alpha.franken.de> (raw)
In-Reply-To: <alpine.LFD.2.03.1309160606110.2176@linux-mips.org>
On Mon, Sep 16, 2013 at 06:54:55AM +0100, Maciej W. Rozycki wrote:
> Thomas, what was the rationale behind arranging things in this way? Did
> you mean to make this code shared among platforms needing it? I would
I really can't remember the reasoning any more, but I guess code sharing
was a reason.
> guess so, but then the copy in arch/mips/dec/prom/ would have to be
> removed and macros in <asm/dec/prom.h> adjusted according to the new API
> which you didn't do in your change.
because I didn't have a running DECstation handy.
> Also why the need for stack
> switching? It looks like an unnecessary complication to me, any firmware
> callbacks exported have to maintain stack integrity or they would be
> unusable. Is that to work around some SNI firmware quirk?
a 64bit kernel with more than CKSEG0 addressable memory may end up having
a stack outside of CKSEG0, which is something the 32bit SNI firmware
doesn't like. I guess the same is true for DECstation, if there is a HW config
with enough memory.
> [And does it work for the SNI in the first place? -- it looks to me like
> `o32_stk' has an alignment problem (8 is required for the stack pointer in
> the o32 ABI though 4 will often be enough to satisfy hardware); but
> perhaps it just happens to get correct alignment by virtue of merely
> always following a data object that enforces it, hmm...]
it worked, but nevertheless fixing the aligment isn't a bad thing.
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
next prev parent reply other threads:[~2013-09-17 8:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-04 22:47 [PATCH] MIPS: DECstation HRT calibration bug fixes Maciej W. Rozycki
2013-09-05 18:08 ` Ralf Baechle
2013-09-06 21:47 ` Maciej W. Rozycki
2013-09-07 7:34 ` Ralf Baechle
2013-09-07 12:48 ` Maciej W. Rozycki
2013-09-07 13:53 ` Geert Uytterhoeven
2013-09-12 12:13 ` Maciej W. Rozycki
2013-09-16 5:54 ` Maciej W. Rozycki
2013-09-17 8:41 ` Thomas Bogendoerfer [this message]
2013-09-17 15:10 ` Maciej W. Rozycki
2013-09-17 15:38 ` Thomas Bogendoerfer
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