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Re: [Qemu-devel] [Please discard the previous mail] System call from a
From: |
Mulyadi Santosa |
Subject: |
Re: [Qemu-devel] [Please discard the previous mail] System call from a Guest Linux |
Date: |
Thu, 4 Feb 2010 02:25:43 +0700 |
Hi Jong
(Sorry, I am not sure how to politely call a Korean name...so
apologize if it turns out to be rude...)
On Thu, Feb 4, 2010 at 1:08 AM, Jong Chun Park <address@hidden> wrote:
> after compilation in the guest OS:
> int main() {
> int fd;
> if (access("hello.txt", R_OK) != 0) {
> exit(0);
> }
> fd=open("hello.txt", O_RDONLY);
> close(fd);
> return 0;
> }
>
> For this simple sequence of system calls, acess() -> open() -> close(), QEMU
> goes through disas_insn() and helper_sysenter() more than 3 times. This
> makes me really confused because I believed those should be called 3 times,
> though. It'd be greatly appreciated in advance if someone helps me out this.
> Thanks a lot,
> Jong
Try to run that compile and run that code under strace (without using
Qemu, I mean), then you'll understand how many system calls are
executed.
clues: opening certain libraries, doing mmap() s and so on
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com