Re: [autotest] vm creation fails (not)

[Gerd Hoffmann <kraxel@redhat.com>]

On 08/05/09 16:05, Michael Goldish wrote:
> Thanks, I managed to reproduce it and I'll send a patch to fix it soon.
> The reason for autotest thinking qemu wasn't alive was that apparently it
> takes time for /proc/$PID/cmdline to reflect the real command used to
> start the process, and I wrongly assumed it was instantaneous.

There is no "command line used to start the process" in unix.

A new process is created using fork().
An process can replace itself with a new executable using execve().

Usual way to start some application in unix is this:
   (1) fork()
   (2) prepare environment (i/o redirection for example)
   (3) execve()

(2)+(3) happen in the new child process created by (1).

/proc/$pid/cmdline will reflect that of course.  It will show the qemu 
command line once execve(qemu) syscall finished.

HTH,
   Gerd