On Saturday 30 Apr 2016 10:05:40 Jonathan Callen wrote: > On 04/30/2016 09:53 AM, Mick wrote: > > On Saturday 30 Apr 2016 08:50:55 Alec Ten Harmsel wrote: > >> On Sat, Apr 30, 2016 at 09:29:08AM +0100, Neil Bothwick wrote: > >>> On Sat, 30 Apr 2016 09:07:29 +0100, Mick wrote: > >>>> I seem to have mislaid my microcode somewhere, in the latest stable > >>>> gentoo kernel: > >>>> > >>>> # grep -i MICROCODE .config > >>>> # > >>> > >>> Grepping .config is unreliable, and always has been. > >> > >> I usually use something like: > >> grep MICROCODE $(find . -name Kconfig) > >> > >> Alec > > > > # grep -i MICROCODE /boot/config-4.4.6-gentoo > > # > > # grep -i MICROCODE .config > > # > > # grep MICROCODE $(find . -name Kconfig) > > ./arch/x86/Kconfig:config MICROCODE > > ./arch/x86/Kconfig:config MICROCODE_INTEL > > ./arch/x86/Kconfig: depends on MICROCODE > > ./arch/x86/Kconfig: default MICROCODE > > ./arch/x86/Kconfig:config MICROCODE_AMD > > ./arch/x86/Kconfig: depends on MICROCODE > > ./arch/x86/Kconfig:config MICROCODE_OLD_INTERFACE > > ./arch/x86/Kconfig: depends on MICROCODE > > # > > > > Now you see it ... now you don't! I am getting really confused. :-/ > > > > Why on this PC the MICROCODE options become available only when I enable > > INITRD, but on other PCs such a problem does not exist? > > The proper way to load microcode into the kernel is now to have it be > part of an initramfs (the initramfs doesn't (I think) have to actually > do anything, just have the microcode firmware in the appropriate > location). This is because some things in userspace (like glibc itself) > only check once for certain CPU features at startup, and newer microcode > will actually disable some of those features on some CPUs (because they > are completely broken anyway). This means that loading the microcode > before any userspace programs run will ensure that applications like > /sbin/init won't crash just because a feature they thought they could > use suddenly disappeared.
Thanks Jonathan for your explanation. I noticed another machine that loaded the MICROCODE as expected, had initrd enabled in the kernel although not used for anything else. I will enable it on this PC too and get on with the next job. -- Regards, Mick
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