Messages in this thread | | | Date | Tue, 20 Jan 2004 23:10:25 +0100 | From | Adrian Bunk <> | Subject | Re: [1/4] better i386 CPU selection |
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On Sat, Jan 17, 2004 at 10:13:37AM +0100, Robert Schwebel wrote:
> Hi,
Hi Robert,
> On Sat, Jan 17, 2004 at 03:15:32AM +0100, Adrian Bunk wrote: > > Besides the AMD Elan cpufreq driver I see nothing where CONFIG_MELAN > > gave you any real difference (except your highest goal is to avoid a > > recompilation when switching from the Pentium 4 to the AMD Elan - but I > > doubt the really "prevents development"). > > > > But I'm not religious about this issue. Let Robert decide, the Elan > > support is his child. > > > > > > > - added optimizing CFLAGS for the AMD Elan > > > > > > There are no such different "optimizations" for ELAN. > > > > What's wrong wih the -march=i486 Robert suggested? > > I've not followed the 2.6 development regarding the arch selection that > closely; let's collect arguments: > > - Is it still possible to run a -march=i486 built kernel on a pentium? > IMHO It would be good to optimize the code for i486, but I'm not that > familiar with how good gcc optimizes for 486 that I can comment this.
yes, since a Pentium supports a superset of the 486 gcc can't optimize for a 486 in a way that the code won't run on a Pentium.
> - I personally work with lots of cross architectures like ARM, so cross > compiling for an embedded system is no problem for me. But if people > want to test stuff on their pentiums I also have no problem with that. > > Other arguments?
The only reason why I sent the patch to make the AMD Elan a separate subarch was the CLOCK_TICK_RATE #ifdef in include/asm-i386/timex.h .
It should be possible to change it to a variable (as with CONFIG_X86_PC9800) if both the Elan and a different cpu are supported if this is really a required use.
If this is the solution you prefer, how would you do runtime detection for the AMD Elan?
> Robert
cu Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed
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