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Old 11-20-2011, 01:14 PM
 
Default Increasing minimum 'i386' processor

On Nov 19, Ben Hutchings <ben@decadent.org.uk> wrote:

> I think it is time to increase the minimum requirement to 586-class, if
> not for wheezy then immediately after.
I agree, it's time to weight the costs and benefits of supporting
obsolete hardware at the expense of most users.

> (Later it should be increased
> further, and eventually i386 should be reduced to a partial architecture
> that may be installed on amd64 systems.)
Yes, but how much later? :-)

--
ciao,
Marco
 
Old 11-20-2011, 01:16 PM
 
Default Increasing minimum 'i386' processor

On Nov 20, Adrian Knoth <adi@drcomp.erfurt.thur.de> wrote:

> On behalf of the multimedia camp, I'd like to point out that we'd love
> to see SSE as the lowest common denominator on the x86 platform.
Can you show a rough list of the relevant packages?
Maybe older CPUs would be too much slow anyway for many of them, so
targetting more recent CPUs than the norm would not hurt.

--
ciao,
Marco
 
Old 11-20-2011, 02:17 PM
Kai Wasserbäch
 
Default Increasing minimum 'i386' processor

Dear Ben,
Ben Hutchings schrieb am 19.11.2011 23:42:
> The i386 architecture was the first in Linux and in Debian, but we have
> long since dropped support for the original i386-compatible processors
> and now require a minimum of a 486-class processor.
>
> I think it is time to increase the minimum requirement to 586-class, if
> not for wheezy then immediately after. (Later it should be increased
> further, and eventually i386 should be reduced to a partial architecture
> that may be installed on amd64 systems.) This would allow the use of
> optimisations and new instructions throughout userland that improve
> performance for the vast majority of users.

I think "in time for Wheezy" would be fine. People with an older CPU will most
likely not have that much fun with newer releases anyway, simply because a lot
of programs tend to get bigger and more power-hungry over time.

Just out of curiosity: are there any numbers available, indicating how many
installations with CPUs with an instruction set < 586 are still in use? Does
popcon collect such information?

Kind regards,
Kai Wasserbäch



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Old 11-20-2011, 02:30 PM
Kai Wasserbäch
 
Default Increasing minimum 'i386' processor

Dear Raphaël,
Raphaël Hertzog schrieb am 20.11.2011 08:40:
> On Sat, 19 Nov 2011, Ben Hutchings wrote:
>> Also possibly:
>> 6. DM&P/SiS Vortex86 and Vortex86SX. These supposedly have all
>> 586-class features except an FPU, and we could probably keep FPU
>> emulation for them.
>
> FWIW, I do run Debian on such systems albeit with a custom kernel.
> Given those CPU tend to be used in an "embedded" context I guess
> it's ok if the official kernel does not support them. But it would be
> nice if Debian's userspace could be kept compatible. Not sure what this
> requires though...

judging from the section you quoted from Ben's e-mail, I'd say you shouldn't be
affected in the short term if the FPU is really the only thing missing to make
it a full 586-class CPU (of course, a further increase to a higher instruction
set class would hit you).
Apart from that I wonder how many "embedded" x86 CPUs (instruction set < 586)
are out there. Are they still sold in current products? If so it might(!) be
worth to keep compatible with them, even if that would mean an additional kernel
build*. On the other hand most embedded kernels are custom build anyway, in
which case "offering the tools" to build a running Debian system should be
enough, right?

* The question here is (again): do we have some numbers on this, that could
guide the decision? If not and the assumption by the kernel maintainers is "few
systems still operational run with CPUs which don't at least support 586
instructions", then I'd find it reasonable to still disable the support in the
kernel. In case a huge amount of systems is still running with such CPUs chances
are good, we're hearing of them then. ;-)

Kind regards,
Kai Wasserbäch



--

E-Mail: curan@debian.org
IRC: Curan
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Old 11-20-2011, 02:39 PM
Timo Juhani Lindfors
 
Default Increasing minimum 'i386' processor

Kai Wasserbäch <curan@debian.org> writes:
> installations with CPUs with an instruction set < 586 are still in use? Does
> popcon collect such information?

popcon does not but smolt does. Unfortunately smotl ITP is still
stuck. Meanwhile you can look at the data it has collected from opensuse
and fedora users:

echo 'select count(*) as c, cpu_model from host group by cpu_model order by c;' | mysql -h localhost -u smoon -p --password=smoon -D smoon > p/smolt/cpu_model_count.txt
=> http://lindi.iki.fi/lindi/smolt/cpu_model_count.txt

Full database dump is at

http://lindi.iki.fi/lindi/smolt/smolt-2011-08-28.dmp.gz

if you want to make your own queries.

-Timo


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Old 11-20-2011, 04:32 PM
Ben Hutchings
 
Default Increasing minimum 'i386' processor

On Sun, 2011-11-20 at 08:40 +0100, Raphael Hertzog wrote:
> On Sat, 19 Nov 2011, Ben Hutchings wrote:
> > Also possibly:
> > 6. DM&P/SiS Vortex86 and Vortex86SX. These supposedly have all
> > 586-class features except an FPU, and we could probably keep FPU
> > emulation for them.
>
> FWIW, I do run Debian on such systems albeit with a custom kernel.
> Given those CPU tend to be used in an "embedded" context I guess
> it's ok if the official kernel does not support them. But it would be
> nice if Debian's userspace could be kept compatible. Not sure what this
> requires though...

As I said, I think they may still be supportable - the kernel config
allows selection of CONFIG_M586TSC and CONFIG_MATH_EMULATION, though
whether the result actually works is another matter.

Ben.

--
Ben Hutchings
Usenet is essentially a HUGE group of people passing notes in class.
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Old 11-20-2011, 04:35 PM
Ben Hutchings
 
Default Increasing minimum 'i386' processor

On Sun, 2011-11-20 at 15:04 +0100, Vincent Danjean wrote:
> Le 20/11/2011 12:56, Adrian Knoth a écrit :
> > On behalf of the multimedia camp, I'd like to point out that we'd love
> > to see SSE as the lowest common denominator on the x86 platform.
> >
> > I'm fully aware that we can't, not even with i586 being the baseline.
> > Since many multimedia applications don't do runtime CPU detection, only
> > amd64 generally provides decent SIMD support to Debian users on x86
> > these days.
> >
> >
> > Long story short: userspace i386 compatibility would suck for
> > multimedia.
>
> Partial multi-arch aware architectures would be the perfect answer here.
> (ie a i686 archive with only package/libs that are improved by using
> the i686 instruction set)
[...]

Yes, this does sound like a good answer, though I don't believe dak is
ready to support partial architectures yet. We already have the ability
to install optimised libraries that are selected automatically by the
dynamic linker, but it would be preferable to have them also selected
automatically by APT.

Ben.

--
Ben Hutchings
Usenet is essentially a HUGE group of people passing notes in class.
- Rachel Kadel, `A Quick Guide to Newsgroup Etiquette'
 
Old 11-20-2011, 04:48 PM
Ben Hutchings
 
Default Increasing minimum 'i386' processor

On Sun, 2011-11-20 at 16:30 +0100, Kai Wasserbäch wrote:
> Dear Raphaël,
> Raphaël Hertzog schrieb am 20.11.2011 08:40:
> > On Sat, 19 Nov 2011, Ben Hutchings wrote:
> >> Also possibly:
> >> 6. DM&P/SiS Vortex86 and Vortex86SX. These supposedly have all
> >> 586-class features except an FPU, and we could probably keep FPU
> >> emulation for them.
> >
> > FWIW, I do run Debian on such systems albeit with a custom kernel.
> > Given those CPU tend to be used in an "embedded" context I guess
> > it's ok if the official kernel does not support them. But it would be
> > nice if Debian's userspace could be kept compatible. Not sure what this
> > requires though...
>
> judging from the section you quoted from Ben's e-mail, I'd say you shouldn't be
> affected in the short term if the FPU is really the only thing missing to make
> it a full 586-class CPU (of course, a further increase to a higher instruction
> set class would hit you).
> Apart from that I wonder how many "embedded" x86 CPUs (instruction set < 586)
> are out there. Are they still sold in current products?

As I said, Soekris still seems to have some for sale, but they are just
using up their remaining stock of CPUs.

> If so it might(!) be
> worth to keep compatible with them, even if that would mean an additional kernel
> build*.

No, there will be no additional kernel flavours. The kernel team is
generally aiming to cover all supported systems with as few different
configurations as possible. Every extra flavour takes substantial space
in the archive and time on autobuilders.

> On the other hand most embedded kernels are custom build anyway, in
> which case "offering the tools" to build a running Debian system should be
> enough, right?
>
> * The question here is (again): do we have some numbers on this, that could
> guide the decision? If not and the assumption by the kernel maintainers is "few
> systems still operational run with CPUs which don't at least support 586
> instructions", then I'd find it reasonable to still disable the support in the
> kernel. In case a huge amount of systems is still running with such CPUs chances
> are good, we're hearing of them then. ;-)

I'm confident there aren't a huge number of systems, but it's really
impossible to tell just how many or few there are.

Ben.

--
Ben Hutchings
Usenet is essentially a HUGE group of people passing notes in class.
- Rachel Kadel, `A Quick Guide to Newsgroup Etiquette'
 
Old 11-20-2011, 04:52 PM
Ben Hutchings
 
Default Increasing minimum 'i386' processor

On Sun, 2011-11-20 at 15:14 +0100, Marco d'Itri wrote:
> On Nov 19, Ben Hutchings <ben@decadent.org.uk> wrote:
>
> > I think it is time to increase the minimum requirement to 586-class, if
> > not for wheezy then immediately after.
> I agree, it's time to weight the costs and benefits of supporting
> obsolete hardware at the expense of most users.
>
> > (Later it should be increased
> > further, and eventually i386 should be reduced to a partial architecture
> > that may be installed on amd64 systems.)
> Yes, but how much later? :-)

At the latest:

wheezy+2 (2016): require 686-class with PAE
wheezy+4 (2020): i386 is a partial architecture

But I think we could be more aggressive than that.

Ben.

--
Ben Hutchings
Usenet is essentially a HUGE group of people passing notes in class.
- Rachel Kadel, `A Quick Guide to Newsgroup Etiquette'
 
Old 11-20-2011, 05:02 PM
Philipp Kern
 
Default Increasing minimum 'i386' processor

On 2011-11-20, Ben Hutchings <ben@decadent.org.uk> wrote:
> As I said, I think they may still be supportable - the kernel config
> allows selection of CONFIG_M586TSC and CONFIG_MATH_EMULATION, though
> whether the result actually works is another matter.

So what are we actually requiring when moving from 486 to 586? From your
listing I guess rdtsc and the presence of a x87 FPU (didn't we already
require that before?). Anything else?

Kind regards
Philipp Kern


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