Re: x86_64 architecture level requirements, x86-64-v2 for openSUSE Factory
On Thursday 2022-07-28 14:58, Dirk Müller wrote:
Shouldn't we drop i586 before dropping any x86_64-v0 class hw?
Feels a bit strange to support most recent and most ancient components, with an uncanny hole in the middle
if we do not drop i586, there is no hole, as hardware incompatible with x86_64-v2 can still run i586.
I like your thinking. We should set the distro level to x86_64-v4 then: Hardware incompatible with x86_64-v4 can still run the i586 binaries.
Hi Jan, Am Do., 28. Juli 2022 um 16:20 Uhr schrieb Jan Engelhardt <jengelh@inai.de>:
if we do not drop i586, there is no hole, as hardware incompatible with x86_64-v2 can still run i586. I like your thinking. We should set the distro level to x86_64-v4 then: Hardware incompatible with x86_64-v4 can still run the i586 binaries.
I hear the irony in this. Okay. let me rephrase: a) select a base level (-v1 or -v2, don't really personally care, I have no -v1 only hardware anymore) b) offer hwcaps overlay like -v3. I think -v4, which essentially requires AVX512 is likely not worth the effort except for some really extreme cases, where the open source projects in questions likely already have customized AVX512 assembly included that is executed when the hardware fits.
On Thu, Jul 28, 2022 at 7:33 AM Dirk Müller <dirk@dmllr.de> wrote:
Hi Jan,
Am Do., 28. Juli 2022 um 16:20 Uhr schrieb Jan Engelhardt <jengelh@inai.de>:
if we do not drop i586, there is no hole, as hardware incompatible with x86_64-v2 can still run i586. I like your thinking. We should set the distro level to x86_64-v4 then: Hardware incompatible with x86_64-v4 can still run the i586 binaries.
I hear the irony in this. Okay. let me rephrase:
a) select a base level (-v1 or -v2, don't really personally care, I have no -v1 only hardware anymore)
b) offer hwcaps overlay like -v3.
This makes sense to me. I don't think the majority of packages will benefit from -v3, but -v2 has been around long enough that it's generally fine and in-line with expected targeted systems.
I think -v4, which essentially requires AVX512 is likely not worth the effort except for some really extreme cases, where the open source projects in questions likely already have customized AVX512 assembly included that is executed when the hardware fits.
As long as Intel continues to segment instructions across CPUs and not include newer AVX instructions in even newly released processors, -v4 will never be realistic. -v3 is already problematic for similar reasons. -- 真実はいつも一つ！/ Always, there's only one truth!
Neal Gompa schrieb:
As long as Intel continues to segment instructions across CPUs and not include newer AVX instructions in even newly released processors, -v4 will never be realistic. -v3 is already problematic for similar reasons.
And it will probably get worse in the future when it will not depend on the actual hardware you have but on your subscription level with the company producing it (and I'm sure that won't be just an Intel story but go across the business), see https://lwn.net/Articles/884876/ Robert Kaiser
participants (4)
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Dirk Müller -
Jan Engelhardt -
Neal Gompa -
Robert Kaiser