From: "Hua Zhong" <hzhong@cisco.com>
To: <root@chaos.analogic.com>, "Davide Libenzi" <davidel@xmailserver.org>
Cc: "Linux kernel" <linux-kernel@vger.kernel.org>
Subject: RE: top stack (l)users for 2.5.69
Date: Wed, 7 May 2003 12:39:28 -0700
Message-ID: <CDEDIMAGFBEBKHDJPCLDOECDDPAA.hzhong@cisco.com>
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> It is my understanding that there is one kernel stack. If there
> is a stack allocated for some "transition", and I guess there
> may be, because of the mail I'm getting, then it has absolutely
> no purpose whatsoever and is wasted valuable non-paged RAM.

I think your understanding is wrong. Each process has its own kernel stack
allocated together with the task_struct in a 8K chunk. At least for 2.4 it
is. I think interrupt handler also uses the current kernel stack.

> The reason why system-call parameters are passed in registers
> is so that we didn't have the overhead of copying stuff from a
> user stack to a kernel stack.
>
> Does anybody know (not guess) if this was stuff added for the
> new non-interrupt 0x80 syscall code? I want to know how a
> simple kernel got corrupted into this twisted thing.
>
> Anybody who has a copy of any of the Intel manuals since '386
> knows that there needs to be only one kernel stack.
>
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
> Why is the government concerned about the lunatic fringe? Think about it.

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