Laszlo, BaseXApicX2ApicLib is intended to be used by platforms that support more >=256 CPUs.
If the current system configuration is < 256 CPUs, then the platform will typically stay in APIC mode. If >= 256 CPUs are detected, then X2 APIC mode can be enabled using the following API. VOID EFIAPI SetApicMode ( IN UINTN ApicMode ) So just adding BaseXApicX2ApicLib to the DSC does not enable X2 APIC mode. You have to add logic to enable X2 APIC mode. I see that QEMU is limited to 255 VCPUs, so the use of BaseXApicLib makes sense. Are OVMF configurations supported with >= 256 VCPUs? Thanks, Mike >-----Original Message----- >From: Laszlo Ersek [mailto:ler...@redhat.com] >Sent: Wednesday, November 04, 2015 2:41 AM >To: Paolo Bonzini; edk2-de...@ml01.01.org; Kinney, Michael D; Fan, Jeff; >Justen, Jordan L >Subject: Re: [edk2] [PATCH v4 18/41] OvmfPkg: select LocalApicLib instance >with x2apic support if SMM_REQUIRE > >On 11/04/15 09:48, Paolo Bonzini wrote: >> >> >> On 03/11/2015 22:00, Laszlo Ersek wrote: >>> + >>> +!if $(SMM_REQUIRE) == TRUE >>> + >LocalApicLib|UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.inf >>> +!else >>> LocalApicLib|UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.inf >>> +!endif >>> + >> >> Can we enable BaseXApicX2ApicLib unconditionally? > >I think I am technically capable of that :), but should we? We haven't >used BaseXApicX2ApicLib thus far in OVMF, so I can't predict at all if >it could regress stuff or not. If it causes problems with the >SMM_REQUIRE build, so be it, that's new stuff, but I wanted to avoid >such a global change for the traditional build. > >I'm not against it, I just don't have experience with BaseXApicX2ApicLib. > >Mike, Jeff, Jordan -- what do you think? Why do separate BaseXApicLib >and BaseXApicX2ApicLib instances exist? And why has OvmfPkg always used >the former? If it has only been for simplicity's sake, and >BaseXApicX2ApicLib is otherwise widely used internally at Intel, then I >think Paolo is right, and we should just keep the OVMF DSCs simple. > >Thanks >Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
