Messages in this thread | | | Subject | Re: 2.6.19-rc5 breaks klogd 1.4.1 | From | Mike Galbraith <> | Date | Thu, 09 Nov 2006 16:25:26 +0100 |
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On Thu, 2006-11-09 at 11:11 +0100, Mike Galbraith wrote: > On Wed, 2006-11-08 at 23:35 -0800, Andrew Morton wrote: > > > And, predictably, reads from /proc/kmsg aren't blocking. > > > > I can't see what might have caused that. Are you sure that 2.6.19-rc4 was > > OK? And are you sure that nothing else has changed on that system? > > Here, both rc4 and rc5 do the same if printk is configured out.
Well duh, of course it does. Testing and _then_ looking at the source was not the correct order in this case :)
> Why do we have a /proc/ksmg when nothing can get to it?
The sensible thing seemed to be to whack it, but when I did that, klogd just switched interfaces, and proceeded to eat 100% cpu doing syslog(0x2, 0xb7fc0008, 0x1ffff) instead. Leaving it in place, but making it block to simulate an empty buffer works fine, but seems kinda cheezy.
Whacking /proc/kmsg, and making sys_syslog() block on read to simulate the empty buffer seemed much better, but SuSE's boot scripts hang when they try to create /var/log/boot.msg ala /sbin/klogd -s -o -n -f /var/log/boot.msg. That seems to work now only because there is always something there to grab.
The correct answer seems to be "fix klogd, or don't disable printk".
-Mike
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