Messages in this thread | | | From | "Khimenko Victor" <> | Date | Sun, 18 Oct 1998 21:25:04 +0400 (MSD) | Subject | Re: Cyrix Detection -- NO SMP, please ????? |
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In <Pine.LNX.3.96.981018115925.22009A-100000@z.ml.org> Gregory Maxwell (linker@z.ml.org) wrote:
GM> My linux is SLLLOOOWWWW.. My linux is SLLLOOOWWWW..
GM> The dists should be shipping two sets of kernels. Both with PPRO opt GM> turned on and MTRR support. This leaves out the i386. SO? What the hell GM> are you doing Running RedHat 5.5 w/ a 2.2 kernel on a i386?!? PPro opt GM> will work on i486+.
I'm not so sure. AFAIK kernel compiled for Pentium (let alone PPro) could do some nasty things under 486 :-(( There are some difference in paging support...
GM> MTRR support must be on w/ PPRO+ SMP because some MBs dont set MTRRs GM> correctly on both CPUs..
MTRR should be compatible with 486-optimized kernel :-)
GM> Most people have UP. The install's failure modes should set the kernel to GM> UP in any case.
Why ? How SMP support could harm in failure mode ? Only if it will prevent kernel from booting :-))
>> GM> No there should be seperate SMP and UP kernels. Do you think that x86 and >> GM> Alpha should run from the same kernel binary? >> >> This will be great but it's almost impossible to do :-((
GM> :) I know how to do it. You enhance the boot loaded so it can boot a 'fat' GM> kernel. (i.e. all the ARCHS catted togeather) The same would work for SMP. GM> I'm not so sure I want 100megs of my HDD eaten up by a fat kernel and fat GM> modules.
Old BIOS'es does not support more then 1.44" floppy image as "boot image" for bootable CD's :-((
GM> I understand that you want all non-exp stuff to work. I do too. APM and GM> SMP are mutually exclusive. There is some alternitive to APM (forget it's GM> name) that will work with SMP. Can you point out ANY OSes that use SMP and GM> APM? :)
Hm. Why Linux should not be first such OS ?
>> Why ? Why my SMP box should be powered all time and could not go to sleep when >> it's not active for long time like UP one ? I'm KNOW that it's a big problem >> to call APM BIOS from SMP kernel (you should stop second processor first, then >> make call -- AFAIK it's the only reliable way to do this; since this will >> require A LOT OF work this is definiteally not 2.2 task if at all). I'm know >> this as programmer but as user I'm confused: why my UP box could turn power off >> itself (without me pressing on "BIG RED BUTTON") while my SMP box with the same >> components except second proc could not ???
GM> I think that that part of APM can be done safely under SMP..
No. You could not call APM BIOS safely under SMP at all :-(( It's possible to stop second proc and call SMP (in theory) but it's unclear if this is worth such troubles. And this is not 2.2 issue anyway :-)
>> I know this. But in "real-world" examples this overhead is pretty small! Of >> course it's not hard to develop special example where such overhead will be >> problem but in most cases this overhead is not a problem...
GM> It is a big difference.
When ? What kind of work you should do to see more then few per cent's difference in speed of SMP and UP kernel on UP comp ?
>> Dists should select right kernel automatically in most cases. Windows NT do >> this for last few years -- why Linux could not do this ? "Joe Average" viewpoint >> of course :-))
GM> It's possible.
It's not possible if we need to find "correct configurations" out of 1'000'000'000'000'000'000'000'000'000'000+ possible configurations (if we had only 100 options in kernel -- now we have more then 100 options there and thus more then 1'000'000'000'000'000'000'000'000'000'000 possible configurations) -- Earth simple does not enough have resources to do this :-(( We should have few (no more then 5-10 and better only one) which will fit 99.9% users... With modules usage of course :-))
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