Any SYSRQ key to force mode switch to console mode when using KMS?
jason.wessel at windriver.com
Wed Oct 6 11:44:48 PDT 2010
On 09/24/2010 10:07 AM, Randy Dunlap wrote:
> On Thu, 23 Sep 2010 18:31:32 +0200 Uwe Bonnes wrote:
> [just adding cc's]
>>>>>>> "Randy" == Randy Dunlap <rdunlap at xenotime.net> writes:
>> Randy> Is CONFIG_DRM_KMS_HELPER enabled in your kernel .config file? If
>> Randy> not, we need to find out how to enable it (there is no kconfig
>> Randy> prompt for it).
>> Yes, it is enabled
>> Randy> Can you check if Alt-Sysrq-H (help) lists V for "force-fb(V)"?
>> Yes, it is listed.
>> And yes, my last experiments where with ALT-CTL-sysreq, so doomed for non
>> function due to operator error.
>> When running X, X.Org X Server 1.9.0 on Thinkpad R50 RV250, Alt-Sysrq-v
>> switches to an all-black display. By console switching with ALT-CLT-F1 I
>> get back to the booting console and ALT-CLT-F7 brings me back to X. Running
>> on the console and calling Alt-Sysrq-v prints
>> SysRq : Restore framebuffer console
>> Is there some omission by the distribution or my setup that Alt-Sysrq-v when
>> running X results in an all-black screen?
>> And when I hit the hibernate problem, the screen stays black even with a
>> console switch after Alt-Sysrq-v
I am not exactly sure what you are looking for but alt-sysrq-v might not
tell you a whole lot because an escape back to the text console that was
not actively receiving printk's or crash data is going to in general
provide you with a black screen.
If you were interested in something a bit more invasive such as a
collecting a process listing or examining the dmesg output you might
consider jumping into kdb.
echo kbd > /sys/module/kgdboc/parameters/kgdboc
Then you would do the "alt-sysrq v" followed by "alt-sysrq g". From
there you could then run dmesg, and your screen would no longer be blank
in theory. :-)
We do have some patches for the RV250 for atomic kernel mode setting
plus kdb support but they are not merged to the mainline kernels as of yet.
More information about the dri-devel