Choosing CONFIG_MIVYBRIDGE in gentoo-kernel [SOLVED]

[dwardo]

Hello,

I've installed gentoo on a old laptop with a 2012 4 core i7 (ivybridge) with just 8Gb of RAM and upgraded sata ssd (currently typing this post with it).
As expected, it has proven slow for compiles so I'm setting up my more recent (less old ?) main gentoo desktop (2019 8 core ryzen 7 with 64Gb of RAM + M2 nvme ssd) as a binhost on which I use a chroot to build the packages with the i7's CFLAGS (thank you resolve-march-native).

I've set up everything to get it working (even binpkg signing !) and world is building and creating binpkgs as we speak .
I just have one issue: I'd like to modify the kernel config using /etc/kernels/config.d to build it for ivybridge instead of the generic X86 default.
Unfortunately the kernel conf does not propose to activate CONFIG_MIVYBRIDGE=y

I've noticed that the gentoo-kernel source configure code arch/x86/Kconfig.cpu is missing the definitions for all the CONFIG_MARCHs and only proposes activating CONFIG_X86_NATIVE_CPU or not (while this would be ok to build on the i7 machine... its no good to build for the i7 but on the ryzen 7 .

Is this a deliberate choice of fedora from which the baseline config is taken ? Why would they do this ?

Is there a way to configure what I'm trying to configure (appart from a patch for arch/x86/Kconfig.cpu in /etc/portage/patches to reintroduce the configuration option [woud that be enough or is more code missing ?] or switching to gentoo-sources) ?

Thanks for any feedback

[pietinger]

Dont enable CONFIG_X86_NATIVE_CPU and use instead one of these two ways:

1. Install the gentoo-sources with Use-flag "experimental"; this will give you options for specific CPUs in the kernel configuration, OR

2. Use your needed march=ivybridge as explained here: https://wiki.gentoo.org/wiki/Kernel/Con ... ion#Kbuild
->

Code: Select all

# make KCFLAGS="-O2 -march=ivybridge"

[dwardo]

I went with 2.

Thank you !

[pietinger]

Thank you !

You are very Welcome !