----- "Gerd Hoffmann" <kraxel@xxxxxxxxxx> wrote: > 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/$PID/cmdline to reflect the real command used > to > > start the process, and I wrongly assumed it was instantaneous. > > There is no "command line used to start the process" in unix. By "command line" I meant the executable name + arguments. In this case the arguments really contain a command line, because the executable started is sh, with '-c' and the qemu command as arguments. > A new process is created using fork(). > An process can replace itself with a new executable using execve(). > > Usual way to start some application in unix is this: > (1) fork() > (2) prepare environment (i/o redirection for example) > (3) execve() > > (2)+(3) happen in the new child process created by (1). > > /proc/$pid/cmdline will reflect that of course. It will show the qemu > > command line once execve(qemu) syscall finished. > > HTH, > Gerd Oh well, I suppose it would be more accurate to say that I didn't take into account the time it takes execve() to finish. kvm_subprocess explicitly calls fork() and execv(), so I should have known better. Thanks again. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
