On Tue Feb 10, 2026 at 9:26 AM CET, Roger Pau Monné wrote: > On Fri, Feb 06, 2026 at 05:15:24PM +0100, Alejandro Vallejo wrote: >> This enables very aggressive DCE passes on single-vendor builds in later >> patches, as it will allow most vendor checks to become statically chosen >> branches. A lot of statics go away and a lot more inlining will be allowed. >> >> A prerequisite for such optimisation is to expand Kconfig to have the >> full set of vendors. Adds Hygon, Centaur, Shanghai and the unknown-vendor >> path. Have Hygon select AMD, and Centaur|Shanghai select Intel. >> >> Not a functional change. >> >> Signed-off-by: Alejandro Vallejo <[email protected]> >> --- >> rfc -> v1: >> * s/depends on/select/ >> * s/UNKNOWN_CPU/UNKNOWN_CPU_VENDOR/ >> * Removed "if unsure, say Y" >> --- >> xen/arch/x86/Kconfig.cpu | 43 +++++++++++++++++++++++++++++++++++++++ >> xen/arch/x86/cpu/Makefile | 6 +++--- >> 2 files changed, 46 insertions(+), 3 deletions(-) >> >> diff --git a/xen/arch/x86/Kconfig.cpu b/xen/arch/x86/Kconfig.cpu >> index 5fb18db1aa..f895cfe97a 100644 >> --- a/xen/arch/x86/Kconfig.cpu >> +++ b/xen/arch/x86/Kconfig.cpu >> @@ -19,4 +19,47 @@ config INTEL >> May be turned off in builds targetting other vendors. Otherwise, >> must be enabled for Xen to work suitably on Intel platforms. >> >> +config HYGON >> + bool "Support Hygon CPUs" >> + select AMD >> + default y >> + help >> + Detection, tunings and quirks for Hygon platforms. >> + >> + May be turned off in builds targetting other vendors. Otherwise, >> + must be enabled for Xen to work suitably on Hygon platforms. >> + >> + >> +config CENTAUR >> + bool "Support Centaur CPUs" >> + select INTEL >> + default y >> + help >> + Detection, tunings and quirks for Centaur platforms. >> + >> + May be turned off in builds targetting other vendors. Otherwise, >> + must be enabled for Xen to work suitably on Centaur platforms. >> + >> +config SHANGHAI >> + bool "Support Shanghai CPUs" >> + select INTEL >> + default y >> + help >> + Detection, tunings and quirks for Shanghai platforms. >> + >> + May be turned off in builds targetting other vendors. Otherwise, >> + must be enabled for Xen to work suitably on Shanghai platforms. >> + >> +config UNKNOWN_CPU_VENDOR >> + bool "Support unknown CPU vendors" >> + default y >> + help >> + This option prevents a panic on boot when the host CPU vendor isn't >> + supported by going into a legacy compatibility mode and not applying >> + any relevant tunings or quirks. >> + >> + Not selecting this options while selecting multiple vendors doesn't >> have >> + any major effect on code size, but selecting a single vendor with this >> + option cleared produces a much smaller build. >> + >> endmenu >> diff --git a/xen/arch/x86/cpu/Makefile b/xen/arch/x86/cpu/Makefile >> index 7cfe28b7ec..84b060aa41 100644 >> --- a/xen/arch/x86/cpu/Makefile >> +++ b/xen/arch/x86/cpu/Makefile >> @@ -3,13 +3,13 @@ obj-y += microcode/ >> obj-y += mtrr/ >> >> obj-y += amd.o >> -obj-y += centaur.o >> +obj-$(CONFIG_CENTAUR) += centaur.o > > Maybe I'm missing some context here, but I think this would break the > build? > > cpu/centaur.c exports centaur_cpu_dev which is referenced from > cpu/common.c, and I don't see you making that reference in > cpu/common.c conditional to CONFIG_CENTAUR being defined? > > I think the same applies to Hygon and Shanghai. > > Thanks, Roger.
Hmm. Yes, these hunks go on the following patch for bisectability. They work due to the AND operation at the switch condition. Cheers, Alejandro
