linux-kernel - Re: [RFC] Try a bit harder to get output on the screen at panic time

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Date:	Thu, 20 May 2010 04:27:07 +0300
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Airlie <airlied@...il.com>,
	James Simmons <jsimmons@...radead.org>
Subject: Re: [RFC] Try a bit harder to get output on the screen at panic
 time

On Thu, 2010-05-20 at 04:13 +0300, Maxim Levitsky wrote: 
> On Wed, 2010-05-19 at 17:34 -0700, Jesse Barnes wrote: 
> > On Fri, 9 Apr 2010 15:10:50 -0700
> > Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> > 
> > > This set of 3 patches makes it a little more likely we'll get panic
> > > output onto the screen even when X is running, assuming a KMS enabled
> > > stack anyway.
> > > 
> > > It gets me from a blank or very sparsely populated black screen at
> > > panic time, to one including the full backtrace and panic output at
> > > panic time (tested with "echo c > /proc/sysrq-trigger" from an X
> > > session).
> > > 
> > > It doesn't cover every case; for instance I think it'll fail when X has
> > > disabled the display, but those cases need to be handled with separate
> > > patches anyway (need to add atomic DPMS paths for instance).
> > > 
> > > Anyway, please test these out and let me know if they work for you.
> > 
> > Ping Linus & Dave again.  Have you guys tried these?  Really, it's cool.
> > 
> Second that, just tested these patches, and these work perfectly.
> One more reason for me to dump nvidia driver for nouveau.


Unfortunately I spoke too soon.


After suspend to ram, system doesn't properly resume now.

My system is based on nvidia G86, I use latest nouveau drivers, and
suspend with compiz running.

I also patched kernel not to do vt switch on suspend/resume:

diff --git a/drivers/gpu/drm/nouveau/nouveau_state.c
b/drivers/gpu/drm/nouveau/nouveau_state.c
index 062b7f6..b3ef08b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_state.c
+++ b/drivers/gpu/drm/nouveau/nouveau_state.c
@@ -31,6 +31,7 @@
#include "drm_crtc_helper.h"
#include <linux/vgaarb.h>
#include <linux/vga_switcheroo.h>
+#include <linux/suspend.h>

#include "nouveau_drv.h"
#include "nouveau_drm.h"
@@ -771,6 +772,8 @@ int nouveau_load(struct drm_device *dev, unsigned
long flags)
                int ret = nouveau_card_init(dev);
                if (ret)
                        return ret;
+
+               pm_set_vt_switch(0);
        }

        return 0;



Best regards,
Maxim Levitsky

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