Date: Thu, 22 Mar 2012 08:13:12 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Alexander Best <arundel@freebsd.org> Subject: Re: still issues with unreadable dmesg output on SMP systems Message-ID: <201203220813.13113.jhb@freebsd.org> In-Reply-To: <20120322101041.GA99431@freebsd.org> References: <20120322101041.GA99431@freebsd.org>
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On Thursday, March 22, 2012 6:10:41 am Alexander Best wrote: > hi there, > > a few years ago there were huge issues with SMP and dmesg output, where > messages from various drivers were output to /dev/ttyv0 without any timing, > which caused a lot of unreadable lines. > > this was fixed and almost all of the dmesg lines i see now look similar to > dmesg on a non-SMP aware kernel. however there still seems to be an issue > within the cd(4) driver. maybe somebody could fix the driver output to match > the drivers, where the dmesg output looks correct (da(4), ada(4), ...). s/fixed/mostly worked around/ The problem is that the work around isn't perfect. The root cause is still not fixed. avg@ has some ideas on better ways to handle this, but it is a bit tricky to get this right since we also dont' want printfs to be delayed too much (and to fix this perfectly requires buffering printf output). -- John Baldwin
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