Debian's i386 Builds Now Require 686-Class CPUs

[starshipeleven]

Knowing Debian, it's pretty easy to just pull down the source and recompile. It's mildly annoying though.

[DeepDayze]

Knowing Debian, it's pretty easy to just pull down the source and recompile. It's mildly annoying though.

Yup, if you can build a 32-bit kernel for the i486 (which covers many of the older CPU's) you can then clap it into a 32-bit LiveUSB of any distro.

[pogson]

This is relevant to my system. I do have some ancient VIA thin clients. I plan to replace them with Odroid-C2 ARMed boards for more RAM, faster CPU/video and gigabit/s networking for half the price I paid so long ago. I'm using an AMD64 terminal server and am considering Lemaker Cello or Huskyboard as a replacement. I left M$ over 15 years ago and 2016 could be the year I go ARMed. So many people are satisfied with the performance they get from ARMed smartphones that I figure a decent ARMed Debian GNU/Linux terminal server with gigabit/s networking should blow them away. The server boards are still light on SATA storage but they have enough CPU power and RAM and cache to do a good job. I think it's past the time we should scrap 32-bit x86 stuff. I still have a printer which has only 32-bit drivers but even it may be close to retirement. I could keep one of the VIA machines as a print server a couple of years longer.

[dbpalan]

They is a weird action. x64 has been deployed over a decade, most people has been using it in "modern" hardware. Those left behind is obviously using "old" hardware and they cannot change them for whatever reasons. Breaking i386 support means cutting the hardware being supported from 1987-2003 to 1998-2003.

If this is due to performance issue, they should upgrade the platform to x64. If this is due to compatibility issue, they should keep all support to the platform.

[starshipeleven]

Yup, if you can build a 32-bit kernel for the i486 (which covers many of the older CPU's) you can then clap it into a 32-bit LiveUSB of any distro.

I suspect that a recompile from source is needed for every package, not just the kernel. They used optimizations that require instruction sets not available in older processors.

Only decent way to install is prepare a rootfs in a chroot from a newer system, you first cross-build the kernel and build-essential packages, then "install" them into the chroot, and from there on it's easy as you can apt-source.

I mean it's not impossible, it's just very annoying.

[starshipeleven]

They is a weird action. x64 has been deployed over a decade, most people has been using it in "modern" hardware. Those left behind is obviously using "old" hardware and they cannot change them for whatever reasons. Breaking i386 support means cutting the hardware being supported from 1987-2003 to 1998-2003.

If this is due to performance issue, they should upgrade the platform to x64. If this is due to compatibility issue, they should keep all support to the platform.

I think they are just assuming that the few people left on such old hardware aren't worth the effort.

[GreatEmerald]

Breaking i386 support means cutting the hardware being supported from 1987-2003 to 1998-2003.

My 32-bit tablet is from 2011. Just saying.

[starshipeleven]

My 32-bit tablet is from 2011. Just saying.

is your 32-bit tablet i386 or i586 (or what processor it has)? they are dropping support only for older 32-bit hardware, not all 32-bit.

Besides, I'm suspecting that it sucked back then and it keeps sucking big way even now.

[jabl]

Hmm, actually I thought CMPXCHG8B but thats i586 already. Might be that solme conditional moves are used for lockfree operations.
I established a baseline for some software a few years ago, which widely uses atomic operations instead of locks. With i586 (some of) these depend on a library (libatomic), with i686 they all are simple cpu instructions. Sorry, would have to dig into it myself for an answer.

Here you can see a list of instructions added with each CPU generation: https://en.wikipedia.org/wiki/X86_instruction_listings . Nothing wrt. atomics added in i686. And yes, i586 added CMPXCHG8B. The big deal was already back in the day when Debian bumped the minimum from i386 to i486. The lack of atomics on i386 was an issue, because then you'd have to add separate i486 versions of all libraries using them, or suffer a rather big performance hit from calling into some support library. IIRC back then they realized that stuff like libstdc++ was already implicitly requiring i486 so dropping i386 support was more like formally documenting the status quo.

And of course, since then the Linux kernel has also dropped i386 support.

That being said, dropping i586 support which is what they're doing now doesn't give particularly big benefits. CMOV, mainly, which isn't such a big deal, really. But evidently they thought that the remaining i586 users were so few and far between that it was still worth it..

[chithanh]

Also there were not many Pentium Pros sold, going i586+MMX would have probably resulted in better performance and fewer dropped systems than going i686+no MMX.