On Saturday, 28 June 2025 18:33:24 British Summer Time Jay Faulkner wrote: > On 6/28/2025 9:38 AM, whiteman808 wrote: > > Is it necessary to reinstall Gentoo if I change CPU or motherboard? If > > not, what steps should be done on the existing Gentoo installation? Do I > > need to do these operations from chroot? > > I'm assuming this is amd64->amd64. > > So the main thing to worry about is CPU compatibility, and your CFLAGS. > If you're using -march=native, there's a chance your system won't work > as compiled. This isn't always true, but these days it's no longer a > guarantee that a newer CPU will have all the features of the old. > > > What I usually do in this case is: > > - set -march=x86-64-v3 (or whatever lowest-common-denominator CPU arch > generic target works) -- > https://wiki.gentoo.org/wiki/Safe_CFLAGS#Generic_psABI_levels can help > with this. - Ensure my system is fully updated, and `emerge > --depclean`'d. - emerge -e @world # this will rebuild your entire system. > > > You can *significantly* reduce the pain of this by using the binary > package host. > > > -JayF
If you have compiled a bespoke kernel strictly specified for the CPU/MoBo hardware the system is running on and them move it to a different CPU/MoBo hardware, you will find the kernel may not boot at all, or it may boot but fail to initialise some hardware, e.g. NICs, graphics card, etc., because it is missing specific drivers and firmware. Using more generic settings will get you a bigger kernel which can boot more hardware than the original.
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