linux-kernel - Re: Why set ORIG_EAX(%esp) to -1 in arch/i386/kernel/entry.S:error

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Date:	Tue, 29 Aug 2006 14:55:53 -0700 (PDT)
From:	Linus Torvalds <torvalds@...l.org>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@...e.de>, Zachary Amsden <zach@...are.com>,
	Chuck Ebbert <76306.1226@...puserve.com>
Subject: Re: Why set ORIG_EAX(%esp) to -1 in arch/i386/kernel/entry.S:error_code?



On Tue, 29 Aug 2006, Jeremy Fitzhardinge wrote:
>
> There doesn't seem much point; nothing seems to use it on the trap-handling
> paths.  Is it a historical left-over?

No. It's important that ORIG_EAX be set to some value that is _not_ a 
valid system call number, so that the system call restart logic (see the 
signal handling code) doesn't trigger.

		Linus
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