Re: Trying to convert old modules to newer kernels

From: James Courtier-Dutton
Date: Fri Dec 21 2007 - 07:24:41 EST


J.A. Magallón wrote:

I need to get rid of -mregparm=3 on gcc's command line. It
is completely incompatible with the standard calling conventions
used in all our assembly-language files in our drivers. We make
very high-speed number-crunching drivers that munge high-speed
data into images. We need to do that in assembly as we have
always done.

Just for curiosity... yep, I understand now you have everything written
in assembler, but why not consider start writing it in C and stop
doing the compiler work (such as pipelining, out of order reordering,
loop unrolling for specific processor, and so on...)

That's what everyone taught me, nowadays you won't be better than the
compiler in anything longer than three lines...


Not true for image processing. compilers are not too good with optimizing mmx and sse algorithms. This is why user space libraries like ffmpeg still use assembly code.
That being said, I don't think sse and mmx are available in kernel space, so I would have suggested doing all the grunt work in userspace would be better for this persons application so that he could use sse and mmx etc.

James

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