Re: [RFC] QR encoding for Oops messages

[Levente Kurusa <levex@linux.com>]

Hi,

On 04/07/2014 05:20 PM, Jason Cooper wrote:
> On Sat, Apr 05, 2014 at 11:11:02AM +0200, Levente Kurusa wrote:
>> Or, we could use core_param and simply have 'oops_qr' or
>> 'qr_oops'. In my humble opinion the latter sounds better.
> 
> Ack.  My original suggestion was focused on 0=disable, >0 is scale.  I
> literally pulled the name from my nether-regions.  :-)

Pushed to Teodora. Hopefully she will pull it soon.

> 
>> Oh and another suggestion, I think placing it in the bottom-right
>> corner would be better since then we wouldn't overwrite some of
>> the timestamps and messages.
> 
> The real text is still sent to the (hopefully written to disk) logs.  If
> a user (or distro) builds with this feature, I would think centered and
> scaled for ease of scanning would be highest priority.

Yup, I'll be traveling on the train a lot this week, so I'll
have plenty of time to implement scaling and centering. Maybe
we could also implement this:

qr_oops=center   (center the QR code with scale 1)
qr_oops=center,3 (center the QR code with scale 3)

'center' could also be 'topleft', 'bottomright', etc.
Or just remain at the KISS rule? (keep it simple)

Any objections?

> 
> I don't think there is a 'safe' part of the framebuffer real estate
> where the QR could be written for all scenarios.  Best to make it easy
> to scan.

Yea we also need to prevent it from happening on panics. Currently on
panics, (i.e. exit when init=/bin/sh) will cause half of the QR code
not rendered on screen due to some reason. It looks like it is due
to scrolling, but I am not sure then why doesn't happen when I
do 'echo c > /proc/sysrq-trigger' which as well causes a panic.

Any ideas why this happens?

-- 
Regards,
Levente Kurusa
PGP: 4EF5D641