Re: 2 more fbcon rotation bugs

["Antonino A. Daplas" <adaplas@gmail.com>]

Knut Petersen wrote:
> 
>> It seems that cfbfillrect and cfbcopyarea were written in a big-endian
>> machine (if I'm not mistaken, by Geert on m68k?) as unaligned access in
>> little endian produces this bug.
>>
>>  
>>
> That patch set fixes my problems with vesafb. For the tested subset of
> possible
> font dimensions and rotation values everything seems to be ok now. But
> maybe
> someone with a  big-endian machine should also verify the code.

In big-endian, the original code gets compiled, so there would be no
regressions.  But does the original code work on them? I don't know yet.

> 
> Isn´t it amazing that code as old as this still contains undetected bugs?

It's quite hard to trigger this bug in an unrotated display because the
usual combination of fontwidths and bpp's typically results in 32-bit
aligned access. And even if the bug is triggered, it is very difficult to
detect as the result will be random pixels at the end of a row of text
which the cursor will overwrite eventually anyway.

Tony

PS: Someone did report before that cfbcopyarea and cfbfillrect does not work
correctly at bpp of 24, but I did not look into it then as I was too lazy
to create a test :-).




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