On 28.09.2021 07:01, Stefano Stabellini wrote: > On Tue, 28 Sep 2021, Wei Chen wrote: >>> -----Original Message----- >>> From: Stefano Stabellini <sstabell...@kernel.org> >>> Sent: 2021年9月28日 9:00 >>> To: Wei Chen <wei.c...@arm.com> >>> Cc: Jan Beulich <jbeul...@suse.com>; xen-devel@lists.xenproject.org; >>> jul...@xen.org; Bertrand Marquis <bertrand.marq...@arm.com>; Stefano >>> Stabellini <sstabell...@kernel.org> >>> Subject: RE: [PATCH 20/37] xen: introduce CONFIG_EFI to stub API for non- >>> EFI architecture >>> >>> On Mon, 27 Sep 2021, Wei Chen wrote: >>>>> -----Original Message----- >>>>> From: Xen-devel <xen-devel-boun...@lists.xenproject.org> On Behalf Of >>> Wei >>>>> Chen >>>>> Sent: 2021年9月26日 18:25 >>>>> To: Jan Beulich <jbeul...@suse.com> >>>>> Cc: xen-devel@lists.xenproject.org; jul...@xen.org; Bertrand Marquis >>>>> <bertrand.marq...@arm.com>; Stefano Stabellini <sstabell...@kernel.org> >>>>> Subject: RE: [PATCH 20/37] xen: introduce CONFIG_EFI to stub API for >>> non- >>>>> EFI architecture >>>>> >>>>> Hi Jan, >>>>> >>>>>> -----Original Message----- >>>>>> From: Xen-devel <xen-devel-boun...@lists.xenproject.org> On Behalf >>> Of >>>>> Jan >>>>>> Beulich >>>>>> Sent: 2021年9月24日 18:49 >>>>>> To: Wei Chen <wei.c...@arm.com> >>>>>> Cc: xen-devel@lists.xenproject.org; jul...@xen.org; Bertrand Marquis >>>>>> <bertrand.marq...@arm.com>; Stefano Stabellini >>> <sstabell...@kernel.org> >>>>>> Subject: Re: [PATCH 20/37] xen: introduce CONFIG_EFI to stub API for >>>>> non- >>>>>> EFI architecture >>>>>> >>>>>> On 24.09.2021 12:31, Wei Chen wrote: >>>>>>>> From: Jan Beulich <jbeul...@suse.com> >>>>>>>> Sent: 2021年9月24日 15:59 >>>>>>>> >>>>>>>> On 24.09.2021 06:34, Wei Chen wrote: >>>>>>>>>> From: Stefano Stabellini <sstabell...@kernel.org> >>>>>>>>>> Sent: 2021年9月24日 9:15 >>>>>>>>>> >>>>>>>>>> On Thu, 23 Sep 2021, Wei Chen wrote: >>>>>>>>>>> --- a/xen/common/Kconfig >>>>>>>>>>> +++ b/xen/common/Kconfig >>>>>>>>>>> @@ -11,6 +11,16 @@ config COMPAT >>>>>>>>>>> config CORE_PARKING >>>>>>>>>>> bool >>>>>>>>>>> >>>>>>>>>>> +config EFI >>>>>>>>>>> + bool >>>>>>>>>> >>>>>>>>>> Without the title the option is not user-selectable (or de- >>>>>> selectable). >>>>>>>>>> So the help message below can never be seen. >>>>>>>>>> >>>>>>>>>> Either add a title, e.g.: >>>>>>>>>> >>>>>>>>>> bool "EFI support" >>>>>>>>>> >>>>>>>>>> Or fully make the option a silent option by removing the help >>> text. >>>>>>>>> >>>>>>>>> OK, in current Xen code, EFI is unconditionally compiled. Before >>>>>>>>> we change related code, I prefer to remove the help text. >>>>>>>> >>>>>>>> But that's not true: At least on x86 EFI gets compiled depending >>> on >>>>>>>> tool chain capabilities. Ultimately we may indeed want a user >>>>>>>> selectable option here, but until then I'm afraid having this >>> option >>>>>>>> at all may be misleading on x86. >>>>>>>> >>>>>>> >>>>>>> I check the build scripts, yes, you're right. For x86, EFI is not >>> a >>>>>>> selectable option in Kconfig. I agree with you, we can't use >>> Kconfig >>>>>>> system to decide to enable EFI build for x86 or not. >>>>>>> >>>>>>> So how about we just use this EFI option for Arm only? Because on >>> Arm, >>>>>>> we do not have such toolchain dependency. >>>>>> >>>>>> To be honest - don't know. That's because I don't know what you want >>>>>> to use the option for subsequently. >>>>>> >>>>> >>>>> In last version, I had introduced an arch-helper to stub EFI_BOOT >>>>> in Arm's common code for Arm32. Because Arm32 doesn't support EFI. >>>>> So Julien suggested me to introduce a CONFIG_EFI option for non-EFI >>>>> supported architectures to stub in EFI layer. >>>>> >>>>> [1] https://lists.xenproject.org/archives/html/xen-devel/2021- >>>>> 08/msg00808.html >>>>> >>>> >>>> As Jan' reminded, x86 doesn't depend on Kconfig to build EFI code. >>>> So, if we CONFIG_EFI to stub EFI API's for x86, we will encounter >>>> that toolchains enable EFI, but Kconfig disable EFI. Or Kconfig >>>> enable EFI but toolchain doesn't provide EFI build supports. And >>>> then x86 could not work well. >>>> >>>> If we use CONFIG_EFI for Arm only, that means CONFIG_EFI for x86 >>>> is off, this will also cause problem. >>>> >>>> So, can we still use previous arch_helpers to stub for Arm32? >>>> until x86 can use this selectable option? >>> >>> EFI doesn't have to be necessarily a user-visible option in Kconfig at >>> this point. I think Julien was just asking to make the #ifdef based on >>> a EFI-related config rather than just based CONFIG_ARM64. >>> >>> On x86 EFI is detected based on compiler support, setting XEN_BUILD_EFI >>> in xen/arch/x86/Makefile. Let's say that we keep using the same name >>> "XEN_BUILD_EFI" on ARM as well. >>> >>> On ARM32, XEN_BUILD_EFI should be always unset. >>> >>> On ARM64 XEN_BUILD_EFI should be always set. >>> >>> That's it, right? I'd argue that CONFIG_EFI or HAS_EFI are better names >>> than XEN_BUILD_EFI, but that's OK anyway. So for instance you can make >>> XEN_BUILD_EFI an invisible symbol in xen/arch/arm/Kconfig and select it >>> only on ARM64. >> >> Thanks, this is a good approach. But if we place XEN_BUILD_EFI in Kconfig >> it will be transfer to CONFIG_XEN_BUILD_EFI. How about using another name >> in Kconfig like ARM_EFI, but use CONFIG_ARM_EFI in config.h to define >> XEN_BUILD_EFI? > > I am OK with that. Another option is to rename XEN_BUILD_EFI to > CONFIG_XEN_BUILD_EFI on x86. Either way is fine by me. Jan, do you havea > preference?
Yes, I do: No new CONFIG_* settings please that don't originate from Kconfig. Hence I'm afraid this is a "no" to your suggestion. Mid-term we should try to get rid of the remaining CONFIG_* which get #define-d in e.g. asm/config.h. Jan
