On Mon, Feb 17, 2025 at 4:44 PM Andrew Cooper <[email protected]> wrote: > > 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. >
I agree with you that changing the default to yes is probably a good idea but I think it would be better to separate making it configurable from changing the default behaviour. Ross
