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Subject: Re: [RFC] CONFIG_FORCE_MINIMALLY_SANE_CONFIG=y
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From: Michal Marek <mmarek@suse.cz>
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Date: Tue, 19 Jan 2016 13:43:08 +0100
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Dne 19.1.2016 v 13:29 Måns Rullgård napsal(a):
> Force-enabling BLK_DEV_INITRD isn't going to make anyone change their
> boot scripts.

If you are on a regular distro, /sbin/installkernel should do the right
thing: Run mkinitrd / dracut and if the tools are recent enough and
there is a microcode update for your CPU, a cpio with the microcode blob
will be prepended to the initrd. So this is more or less covered.


> I'd also like to get a coherent answer to why microcode update is 
> preferably done from an initrd as opposed to shortly after mounting
> a regular disk.  My systems seem perfectly happy doing the latter.

It's not even done *from* the initrd but way earlier. We learned the
hard way when Intel released a microcode update for Haswell which
disabled TSX: Userspace did not expect the feature flags to change and
previously valid instructions to start trapping. This can in principle
happen again and with any vendor.

Michal