On Friday 12 March 2010 04:29 am, Kostik Belousov wrote: > On Thu, Mar 11, 2010 at 06:15:07PM -0500, Jung-uk Kim wrote: > > On Thursday 11 March 2010 04:55 pm, Marcel Moolenaar wrote: > > > On Mar 11, 2010, at 1:24 PM, Jung-uk Kim wrote: > > > > While I was debugging syscalls, I found a very useful field > > > > in struct thread, td_errno. It seems it was added for dtrace > > > > but it is only populated on amd64 and i386. Is the attached > > > > patch acceptable for maintainers of other platforms? > > > > > > Isn't it better to do it in cpu_set_syscall_retval()? > > > That way you catch all cases, plus you can save the > > > translated error as well... > > > > I just took amd64/i386 as an example and I was not sure whether > > it was meant to store translated error or not. Does anyone with > > DTrace internal knowledge answer the question? > > I do not know that much about DTrace, but it seems that setting > td_errno in cpu_set_syscall_retval() is too late. Dtrace has a > probe after the syscall return, and it is called right before > cpu_set_syscall_retval() can be reasonably called. The probe only > issued for syscall that goes into sysent.
Ah, I can see that now. So, if/when we implement DTrace SYSCALL provider for other arches, this is the right place. :-) Thanks! Jung-uk Kim _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
