On 17/02/2025 4:08 pm, Ross Lagerwall wrote: > A lot of systems automatically add microcode to the initrd so it can be > useful as a vendor policy to always scan for microcode. Add a Kconfig > option to allow setting the default behaviour. > > The default behaviour is unchanged since the new option defaults to > "no". > > Signed-off-by: Ross Lagerwall <[email protected]>
I'm pretty sure this is safe on 4.20. Prior versions of Xen need the fix to make idx/scan be mutually exclusive, which hasn't been backported yet IIRC. > --- > xen/arch/x86/Kconfig | 11 +++++++++++ > xen/arch/x86/cpu/microcode/core.c | 2 +- > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig > index 9cdd04721afa..b806d8bc3319 100644 > --- a/xen/arch/x86/Kconfig > +++ b/xen/arch/x86/Kconfig > @@ -383,6 +383,17 @@ config ALTP2M > > If unsure, stay with defaults. > > +config UCODE_SCAN_DEFAULT > + def_bool n > + prompt "Scan for microcode by default" > + help > + During boot, Xen can scan the multiboot images for a CPIO archive > + containing CPU microcode to be loaded. ", which is Linux's mechanism for early microcode loading." This is quite an important point to cover. > + > + Enabling this option will cause Xen to scan for it by default. > + > + If unsure, say N. Personally I don't like this "If unsure", because it's almost always redundant with the default. In this case, it really ought to be "set if you have a Linux dom0", which in turn begs the question as to whether it ought to be bool y. ~Andrew
