[Top] [All Lists]

Re: Decstation broken Was: CVS linux

To: Ralf Baechle <>
Subject: Re: Decstation broken Was: CVS linux
From: "Maciej W. Rozycki" <>
Date: Mon, 2 Oct 2000 13:59:03 +0200 (MET DST)
Cc: Florian Lohoff <>,
In-reply-to: <>
Organization: Technical University of Gdansk
On Sat, 30 Sep 2000, Ralf Baechle wrote:

> >  Well, I asked for testing before the commit, but nobody bothered to write
> > anything, so I assumed everything is correct, sigh...
> Not sigh ...  The lesson that not speaking up is a also wrong!

 Well, if nobody reports a problem with a patch, it means it's either fine
or nobody bothered to test it.  For me both cases mean it's OK to apply

> The ddiv usage outside of do_div / do_div64_32 is actually ok because

 But can't we receive an exception for some reason???

> interrupts are always disabled.  We don't have the same guarantee for
> do_div / do_div64_32 calls.

 Yep -- it's used for printk.

> Hmm...  We got two error scenarios left - bus errors and cache errors.  If
> we get one of those doomsday is near anyway ...  Anyway, these are rare,
> so we rather make these exception handlers pay the price.

 I'd see two approaches: either wipe 64-bit code out completely (clean and
elegant -- I'd vote for it, even though there is performance penalty) or
disable interrupts around the 64-bit division (the window would be small
and it would still be a performance win, but it's ugly as hell).  What do
you think? 


+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+        e-mail:, PGP key available        +

<Prev in Thread] Current Thread [Next in Thread>