Hi,
On 11-07-18 17:42, Daniel Vetter wrote:
On Wed, Jul 11, 2018 at 5:35 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Hi,
On 11-07-18 17:28, Daniel Vetter wrote:
On Wed, Jul 11, 2018 at 5:14 PM, Hans de Goede <hdegoede@xxxxxxxxxx>
wrote:
Hi,
On 11-07-18 17:07, Thomas Zimmermann wrote:
Hi
Am 11.07.2018 um 16:52 schrieb Steven Rostedt:
What if you make lockless_register_fb visible to fbcon, and then we can
have a macro:
There are more of these macro invocations under drivers/tty/vt, which
also mess up the log during debugging.
Hmm, so this option is already broken (in a way) then, my first reaction
to your mail was that we should just remove that option. But that seemed
a bit harsh to me so I've been working on a fix for the last 10 minutes
or so.
But if it is already broken I'm tempted to just remove the option and
be done with it. We really need less cruft in the fbdev/fbcon code not
more.
Please don't remove it, it makes debugging kms driver issues on
initial modeset (which is usually run from framebuffer_register, while
hodling the console_lock) impossible.
OK, so if we don't remove it, we should probably make it so that it
can be used without triggering any WARN_ONs, which would require changing
the existing WARN_CONSOLE_UNLOCKED() so that the calls from
drivers/tty/vt/vt.c
also do not trigger it ?
I guess one can just ignore the oopses when debugging, but debugging surely
would be easier if there are just no oopses ?
I'd say let's only bother with the ones in fbcon.c. Avoids the trouble
with having to expose the fb module option to vt.c somehow.
The plan was actually do the things the other way around, add a flag to
vt.c which when set disables the WARN_ON calls and then have fbdev[.ko]
set that when the fb.lockless_fb_register option is set.
The ones
in vt.c are as old as the git history (from a quick check at least),
and in my debugging they never have been annoying (or I somehow didn't
ever hit them, not idea).
There is a #if 1 #define #else #define empty around the WARN_CONSOLE_UNLOCKED()
call in include/linux/console.h I've the feeling that is there as a hack
to be able to quickly disable the WARN_ONs when debugging.
Have you seen Steven's suggestion which he send about the same time
as your mail I'm replying to here ? I personally think that doing
something like that makes sense (for as long as we have the need
for the lockless_fb_register debug hack).
Note I've 2 patches ready to go to only fix this in fbcon.c, but I
think a more thorough fix makes sense.
Regards,
Hans
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