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Message-ID: <4F7EA84C.7050700@suse.cz>
Date: Fri, 06 Apr 2012 10:24:44 +0200
From: Jiri Slaby <jslaby@suse.cz>
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To: Xin Tong <xerox.time.tech@gmail.com>
CC: linux-kernel <linux-kernel@vger.kernel.org>,
        Jiri Slaby <jirislaby@gmail.com>
Subject: Re: syscall descriptor table
References: <CALKntY2MONLeRvXs2xdamSAQeWDs4ERHjWuCxNL8_QRrHwVhqg@mail.gmail.com>
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On 04/05/2012 11:55 PM, Xin Tong wrote:
> Can anyone please describe to me how x86 syscall works ( i.e. how it
> is dispatched to the correct function) on x86 ?
> 
> mov $1, %eax   ;; __NR_exit = 1
> mov $42, %ebx  ;; status = 42
> sysenter       ;; perform the syscall!
> 
> what does the sysenter instruction do ? what is the difference aganst int 0x80.

Please refer to some processor manual. For example: Intel 64 and IA-32
Architectures Software Developer’s Manual. For the entry point see
ia32_sysenter_target in arch/x86/kernel/entry_32.S for x86_32 or
arch/x86/ia32/ia32entry.S for x86_64 with 32-bit binary.

regards,
-- 
js
suse labs