dev-qt/qtbase-6.7.3-r2 fails to compile [SOLVED]

[dubdinox]

Hello everyone! I was trying to update my system and for some reason qt failed to compile.
I tried to update by doing:

Code: Select all

doas emaint -a sync
doas emerge -avuDN @world

The outputs of emerge --info '=dev-qt/qtbase-6.7.3-r2::gentoo', emerge -pqv '=dev-qt/qtbase-6.7.3-r2::gentoo' and the build log are available here:

https://paste.rs/UhXsm.txt --info
https://paste.rs/P4PkT.txt -pqv
https://files.offshore.cat/Hd9swBXl.log build log

What should I do?

[bstaletic]

The build log has been truncated.

[dubdinox]

Oops, sorry. I've updated the link.

[GDH-gentoo]

Hello everyone! I was trying to update my system and for some reason qt failed to compile.
[...]
https://files.offshore.cat/Hd9swBXl.log build log

Here's the failure:

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>>> Configuring source in /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3 ...
...
-- Configure summary:

Building for: linux-g++ (x86_64, CPU features: abm adx aes avx avx2 bmi bmi2 cx16 f16c fma fsgsbase lzcnt movbe pclmul popcnt prfchw rdpid rdrnd rdseed sha sse3 ssse3 sse4a sse4.1 sse4.2 sse4)
...
>>> Source configured.
>>> Compiling source in /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3 ...
...
[213/748] cd /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui && /usr/bin/cmake -E make_directory vulkan && /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/lib64/qt6/libexec/qvkgen /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3/src/gui/vulkan/vk.xml /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3/src/gui/vulkan/licenseheader.h.in /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui/vulkan/qvulkanfunctions
FAILED: src/gui/vulkan/qvulkanfunctions.h src/gui/vulkan/qvulkanfunctions_p.h src/gui/vulkan/qvulkanfunctions_p.cpp /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui/vulkan/qvulkanfunctions.h /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui/vulkan/qvulkanfunctions_p.h /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui/vulkan/qvulkanfunctions_p.cpp 
cd /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui && /usr/bin/cmake -E make_directory vulkan && /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/lib64/qt6/libexec/qvkgen /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3/src/gui/vulkan/vk.xml /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3/src/gui/vulkan/licenseheader.h.in /var/tmp/portage/dev-qt/qtbase-6.7.3-r2/work/qtbase-everywhere-src-6.7.3_build/src/gui/vulkan/qvulkanfunctions
WARNING: CPU random generator seem to be failing, disabling hardware random number generation
WARNING: RDRND generated: 0xffffffff 0xffffffff 0xffffffff 0xffffffff
Incompatible processor. This Qt build requires the following features:
    rdrnd rdseed

Maybe someone who knows Qt6 better can help.

[dubdinox]

Huh, this doesn't make a lot of sense. I just upgraded my processor today from a Ryzen 5 2600 to a Ryzen 7 3600x (sorry I didn't mention that in the first message) and I thought the architecture would still be amd64.
I guess since it's complaining about missing features I'll try running cpuid2cpuflags and updating again. I'll report back when I do that.

[dubdinox]

Huh, this doesn't make a lot of sense. I just upgraded my processor today from a Ryzen 5 2600 to a Ryzen 7 3600x and I thought the architecture would still be amd64.
I guess since it's complaining about missing features I'll try running cpuid2cpuflags and updating again. I'll report back when I do that.

This did not help. However, I discovered that there's a cpu flag similar to "rdrnd", it's "rdrand".

[Ionen]

"Likely" same as https://bugs.gentoo.org/922498 which is caused when -march=native enables rdrnd but the kernel disables it due to a seemingly buggy implementation for that CPU. You likely have something like that in your dmesg:

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[    0.000000] RDRAND is not reliable on this platform; disabling.

And "rdrand" probably isn't listed in /proc/cpuinfo after that.

Like the kernel Qt6 doesn't seem to like that, and unfortunately we don't currently have auto-detection for that situation setup to trigger a workaround.

...so you may want to use "-march=native -mno-rdrnd" to stop gcc/clang from enabling it (probably a good idea regardless of Qt6 if it's "not reliable"), in case of Qt6 it will also trigger another workaround which should further ensure it builds fine.

Edit: also rdrnd and rdrand are the same thing, it's just named differently in a few areas (the compiler flag is rdrnd, /proc/cpuinfo is rdrand, etc...)

[dubdinox]

...so you may want to use "-march=native -mno-rdrnd" to stop gcc/clang from enabling it (probably a good idea regardless of Qt6 if it's "not reliable"), in case of Qt6 it will also trigger another workaround which should further ensure it builds fine.

So I should set the -mno-rdrnd flag, update, and then I can remove it? Or does it have to be there from that point on?

seemingly buggy implementation for that CPU

Also, I did a bit of googling and found out that updating the microcode might fix that, but reinstalling linux-firmware did not help. Maybe this is because the update is not in the gentoo repositories yet?

[Ionen]

linux-firmware is already at the latest version gentoo's repos (barely 2 weeks old, there's the live ebuild for newer but that's a long shot), whether it can help or not for that specific cpu I don't know.

And yes, it'd have to be kept for as long as it fails to build (for the user in that bug report, it been failing since qtbase-6.6.1 and they still need it today) -- may want to try removing it when the kernel stops giving that message saying that it disables it. Possible that Qt (or Gentoo) will do workarounds eventually but well.

[dubdinox]

Alright, thank you for your help. I've set the flag and now qt builds fine. I'll mark the thread as solved.