Re: Linux-asm (was A patch for linux 2.1.127)

["Richard B. Johnson" <root at chaos dot analogic dot com>]

On Sun, 15 Nov 1998, Riccardo Facchetti wrote:

> On Sat, 14 Nov 1998, Richard B. Johnson wrote:
[SNIPPED]
> 
> I have read your paper, the C code and the Assembly code.
> 
> No problems understanding C code but Assembly ... I have programmed in 16
> bit Intel Assembly long time ago (but I am not a real Assembly programmer) 
> and I am able to follow (sort of) the instruction paths. IMHO the real
> problem is that Assembly need an Assembly programmer to be fully 
> understood and mantained while C is much more easy to mantain. Even more,
> an Assembly programmer can mantain C code while a C programmer may not be
> able to mantain asm code. We need a portable and mantainable kernel. Of
> course I can imagine that for some well defined code paths (like fast
> default cases) or counting functions (like checksumming) asm equivalents
> can be the best solution, but there is a limit at this one too:
> fast asm code for i386 != i486 != P5 != P6 so there should be something
> like:
> 
> #if defined(i386)
> #include "fasti386.S"
> #elif defined(i486)
> #include "fasti486.S"
> #elif defined(P5)
> #include "fastP5.S"
> #elif defined(P6)
> #include "fastP6.S"
> else
> #include "slow.c"
> #endif
> 
This might be a bit extreme, but I get your point!

> and we need someone that is willing to mantain all the different
> implementations in C and in asm and maybe write new ones for P7, P8 etc
> etc. To add more complexity someone should provide Alpha assembly version
> and MIPS and SPARC32 and SPARC64 and motorola etc etc. This is okay for
> something like checksumming but IMHO it will be a real pain if someone
> will come out rewriting e.g. filesystem code in Assembly.
> In this case I say slow C code is better than superfast Assembly code.
> 
> OTOH I've enjoyed your paper Assembly Language, good work :)
> 
> Ciao,
> 	Riccardo.
>
Thanks!


Cheers,
Dick Johnson
                 ***** FILE SYSTEM WAS MODIFIED *****
Penguin : Linux version 2.1.127 on an i586 machine (66.15 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.