* [Buildroot] Xeon variant for x86_64 target
@ 2021-03-22 8:39 Atilla Filiz
0 siblings, 0 replies; 4+ messages in thread
From: Atilla Filiz @ 2021-03-22 8:39 UTC (permalink / raw
To: buildroot
Hello
I am preparing a config for an Intel Xeon D based target. There is no Xeon
variant available in the 2021.02 release. I am not very familiar with the
x86 family but I want to create a pro[er variant if possible.
I see the build variant selects certain flags. E.g. Atom selects
BR2_X86_CPU_HAS_MMX [=y] && BR2_X86_CPU_HAS_SSE [=y] &&
BR2_X86_CPU_HAS_SSE2 [=y] && BR2_X86_CPU_HAS_SSE3 [=y] &&
BR2_X86_CPU_HAS_SSSE3 [=y]
What else does this variant selection affect? I assume a few additional
build flags to pass on GCC? Maybe some kernel build options?
How does one go about creating a proper x86_64 variant?
--
Atilla Filiz
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* [Buildroot] Xeon variant for x86_64 target
@ 2021-03-22 11:23 Atilla Filiz
2021-04-07 18:31 ` Arnout Vandecappelle
0 siblings, 1 reply; 4+ messages in thread
From: Atilla Filiz @ 2021-03-22 11:23 UTC (permalink / raw
To: buildroot
Hello
I am preparing a config for an Intel Xeon D based target. There is no Xeon
variant available in the 2021.02 release. I am not very familiar with the
x86 family but I want to create a pro[er variant if possible.
I see the build variant selects certain flags. E.g. Atom selects
BR2_X86_CPU_HAS_MMX [=y] && BR2_X86_CPU_HAS_SSE [=y] &&
BR2_X86_CPU_HAS_SSE2 [=y] && BR2_X86_CPU_HAS_SSE3 [=y] &&
BR2_X86_CPU_HAS_SSSE3 [=y]
What else does this variant selection affect? I assume a few additional
build flags to pass on GCC? Maybe some kernel build options?
How does one go about creating a proper x86_64 variant?
--
Atilla Filiz
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* [Buildroot] Xeon variant for x86_64 target
[not found] <mailman.16066.1616404411.250923.buildroot@busybox.net>
@ 2021-03-22 16:43 ` Andreas Ziegler
0 siblings, 0 replies; 4+ messages in thread
From: Andreas Ziegler @ 2021-03-22 16:43 UTC (permalink / raw
To: buildroot
Hi Atilla,
> I am preparing a config for an Intel Xeon D based target. There is no
> Xeon
> variant available in the 2021.02 release. I am not very familiar with
> the
> x86 family but I want to create a pro[er variant if possible.
You need to specify the processor architecture inside the Linux kernel
separately (Processor type -> Processor family).
Since Linux puts Core 2 and (newer) Xeon in one setting, you should be
fine with Core 2 for Buildroot also.
Regards,
Andreas
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Buildroot] Xeon variant for x86_64 target
2021-03-22 11:23 Atilla Filiz
@ 2021-04-07 18:31 ` Arnout Vandecappelle
0 siblings, 0 replies; 4+ messages in thread
From: Arnout Vandecappelle @ 2021-04-07 18:31 UTC (permalink / raw
To: buildroot
Hi Atilla,
On 22/03/2021 12:23, Atilla Filiz wrote:
> Hello
>
> I am preparing a config for an Intel Xeon D based target. There is no Xeon
> variant available in the 2021.02 release. I am not very familiar with the x86
> family but I want to create a pro[er variant if possible.
>
> I see the build variant selects certain flags. E.g. Atom selects
> BR2_X86_CPU_HAS_MMX [=y] && BR2_X86_CPU_HAS_SSE [=y] && BR2_X86_CPU_HAS_SSE2
> [=y] && BR2_X86_CPU_HAS_SSE3 [=y] && BR2_X86_CPU_HAS_SSSE3 [=y]
>
> What else does this variant selection affect? I assume a few additional build
> flags to pass on GCC? Maybe some?kernel?build options?
>
> How does one go about creating a proper x86_64 variant?
The only thing that is relevant, really, is the gcc -march option. You have to
find out what the Xeon corresponds to. This determines the BR2_GCC_TARGET_ARCH
option. Of course, the easiest for everybody is if you name the buildroot option
the same as the -march option. There's a StackOverflow answer [1] that lists the
recent Xeons, but only Xeon E, not Xeon D. So you'll have to browse through
Intel's websites to find which type it is.
As to the SSE stuff: that's only relevant to pass in configure options to
ffmpeg and the like. I believe it's just to tell ffmpeg which assembly code it's
allowed to use. You can easily find which instruction types are supported in the
GCC man page, and in /proc/cpuinfo if you have a running kernel.
Regards,
Arnout
[1]
https://stackoverflow.com/questions/943755/gcc-optimization-flags-for-xeon#25095818
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2021-03-22 16:43 ` [Buildroot] Xeon variant for x86_64 target Andreas Ziegler
2021-03-22 11:23 Atilla Filiz
2021-04-07 18:31 ` Arnout Vandecappelle
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2021-03-22 8:39 Atilla Filiz
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