From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from ud10.udmedia.de ([194.117.254.50] helo=mail.ud10.udmedia.de) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VIxfZ-00007n-6c for kexec@lists.infradead.org; Mon, 09 Sep 2013 09:22:06 +0000 Date: Mon, 9 Sep 2013 11:21:40 +0200 From: Markus Trippelsdorf Subject: Re: [PATCH 0/3] drm/radeon kexec fixes Message-ID: <20130909092140.GA359@x4> References: <20130908120947.GA360@x4> <87bo42eswi.fsf@xmission.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87bo42eswi.fsf@xmission.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: Alex Deucher , kexec@lists.infradead.org, dri-devel@lists.freedesktop.org On 2013.09.08 at 17:32 -0700, Eric W. Biederman wrote: > Markus Trippelsdorf writes: > > > Here are a couple of patches that get kexec working with radeon devices. > > I've tested this on my RS780. > > Comments or flames are welcome. > > Thanks. > > A couple of high level comments. > > This looks promising for the usual case. > > Removing the printk at the end of the kexec path seems a little dubious, > what of other cpus, interrupt handlers, etc. Basically estabilishing a > new rule on when printk is allowed seems a little dubious at this point, > even if it is a useful debugging trick. OK. I will drop this patch. It doesn't seem to be necessary, because I cannot reproduce the printk related hang anymore. > Having a clean shutdown of the radeon definitely seems worth doing, > because the cases where we care abouty video are when a person is in > front of the system. Yes. But please note that even with radeon_pci_shutdown implemented, I still get ring test failures on roughly every eighth kexec boot: [drm:r600_dma_ring_test] *ERROR* radeon: ring 3 test failed (0xCAFEDEAD) radeon 0000:01:05.0: disabling GPU acceleration That's definitely better than the current state of affairs, with ring test failures on every second boot. But I haven't figured out the reason for these failures yet. It's curious that once a ring test failure occurs, it will reliably fail after each kexec invocation, no matter how often repeated. Only a reboot brings the machine back to normal. > I don't know if you want to remove the sanity checks. They seem cheap > and safe regardless. Are they expensive or ineffective? Moreover if > they work a reasonable amount of the time that means that the kexec on > panic case (where we don't shut anything down) can actually use the > video, and that in general the driver will be more robust. I don't > expect anyone much cares as kexec on panic is mostly used to just write > a core file to the network, or the local disk. But if it is easy to > keep that case working most of the time, why not. IIRC Alex said the sanity checks are expensive and boot-time could be improved by dropping them. Maybe he can chime in? -- Markus _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec