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Message-ID: <48A0920B.30306@zytor.com>
Date: Mon, 11 Aug 2008 12:24:59 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Ingo Molnar <mingo@...e.hu>
CC: Suresh Siddha <suresh.b.siddha@...el.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Wolfgang Walter <wolfgang.walter@...m.de>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"viro@...IV.linux.org.uk" <viro@...iv.linux.org.uk>,
"vegard.nossum@...il.com" <vegard.nossum@...il.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem
with fpu state changes
Ingo Molnar wrote:
> * Suresh Siddha <suresh.b.siddha@...el.com> wrote:
>
>> Reported-and-bisected-by: Wolfgang Walter <wolfgang.walter@...m.de>
>> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
>
> no fundamental objection to the x86 bits.
>
> shouldnt this:
>
> + if (!in_interrupt())
> + return 0;
>
> just be eliminated and the cr0/TS save/restore be made unconditional?
> irq-assymetric APIs are not nice in general.
>
> Reading/setting cr0 isnt _that_ slow. (or if it is, by how much does it
> slow things down, exactly?)
>
Setting it is relatively slow. I think that's part of the reason for
special instructions to muck with the TS flag.
Reading it might be slow on obsolete processors.
-hpa
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