HI, > On 2 Dec 2024, at 20:38, Julien Grall <[email protected]> wrote: > > Hi Jan, > > On 02/12/2024 07:52, Jan Beulich wrote: >> On 30.11.2024 18:15, Julien Grall wrote: >>> On 29/11/2024 22:12, Volodymyr Babchuk wrote: >>>> Jan Beulich <[email protected]> writes: >>>>> On 29.11.2024 02:49, Volodymyr Babchuk wrote: >>>>>> --- a/config/arm64.mk >>>>>> +++ b/config/arm64.mk >>>>>> @@ -5,6 +5,10 @@ CONFIG_XEN_INSTALL_SUFFIX := >>>>>> CFLAGS += #-marm -march= -mcpu= etc >>>>>> +ifeq ($(clang),y) >>>>>> +CFLAGS += -target aarch64 -march=armv8-a >>>>>> +endif >>>>> >>>>> Why is this dependent on (just?) $(clang), not (also?) $(llvm)? >>>> >>>> Because this parameter is handled by clang only. There is no harm in >>>> providing it explicitly. When building on arm64, value of this parameter >>>> will match the default value for the platform. When building on x86, we >>>> need to tell clang that it should generate arm64 code anyways. There is >>>> no reason in trying to make ARM build with x86 instruction set. >>>> >>>>> Also >>>>> this affects both toolstack builds and hypervisor. Is applying -march >>>>> like this actually appropriate for the toolstack? >>>> >>>> This is a good question. I can't see why this can't be appropriate for >>>> toolstack. I.e. what bad can happen when building the toolstack. >>> >>> In the future, we may want to build the tools for Armv8-M. So I think >>> the -march should also applies for the toolstack. >> Perhaps I don't know enough of the Arm world, but: Wouldn't it be possible >> to build a tool stack suitable for a wide range for Arm64 flavors, while >> requiring more targeted hypervisor binaries? > > Good question. There are some commonnality between ARMv8-M and ARMv8-R but I > am not sure whether it means we could use -march=armv8-a build and run on > ARMv8-M. Adding Ayan and Luca.
AFAIK a binary compiled for armv8-a aarch64 will work also on armv8-r aarch64 since they share almost everything apart from some MPU registers, instead in order to work on armv8-m we might need to pass the appropriate march Cheers, Luca
