Suggestion on bug reporting with KDL photos

[Guest One]

Many people send photos of kernel debug screen to trac. These photos are barely readable sometimes. I think it would be easier to work with such reports if kernel debugger could represent part of it's message buffer in "photo friendly" format, displaying QR-code for example, or some similar way. Photo of QR-code could be converted back to text easily and it contains error correction data.

It's just a suggestion, I do not know if it is technically possible to implement such thing.

[axeld]

It would be possible, yes.

[pulkomandy]

QRCodes only allows for 255 characters... how many of them could we fit on screen ? That would'nt make a lot of data available.

[Guest One]

Replying to pulkomandy:

QRCodes only allows for 255 characters... how many of them could we fit on screen ? That would'nt make a lot of data available.

I believe that QR code allows to store up to ~4K ascii characters or ~2k random binary data. ​ABOUT_QRCODES.

I agree, QR mark of reasonable size (for proposed usage) is limited by ~300-400 encoded symbols, but in many cases it could be helpful.

There are other 2D code standards, but AFAIK QR code is the best by information density.

[phoudoin]

Yep, it's up to 4 296 ascii chars.

For those interested, here a QR encoder written in C, under public domain / CC0, which we could use even statically linked into kernel:

​http://www.norisys.jp/libqr/

[Guest One]

expirement on qr-codes: original

[Guest One]

expirement on qr-codes: photo1

[Guest One]

expirement on qr-codes: photo 2

[Guest One]

Well, I've made some experimentation on real life data.

I took a real dmesg from my linux laptop, made a screenshot, encoded first 20 lines, combined it with screenshot and made two photos by two different cell phones. (Images attached to ticket)

Next, I cut QR codes from photos and tried restore text by ​online decoder.

Only the fourth sequence were restored from the first photo, but entire data were successfully restored from the second.

Conclusion: idea could have some limited use.

[bonefish]

Replying to Guest One:

Only the fourth sequence were restored from the first photo, but entire data were successfully restored from the second.

Conclusion: idea could have some limited use.

I don't know what "sequences" you're referring to here, but in both pictures the text can be read well enough, so I don't really see the advantage of the QR codes, if they work worse than the status quo.

Moreover with the debug syslog feature the KDL output can be stored relatively easily to disk, with the only restrictions that (1) a FAT32 partition/USB stick is required and (2) that a warm reboot is possible.

[mmlr]

I've added that feature in hrev44275 and refined it some in the following revisions. The ReportingBugs wiki page has been updated to include a reference to the blog post explaining the details.