Re: [PATCH for-4.14] x86/shim: Fix defconfig selection and trim the build further

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.06.2020 19:09, Andrew Cooper wrote:
> Several options (TBOOT, XENOPROF, Scheduler) depend on EXPERT to be able to
> deselect/configure.
> 
> Enabling EXPERT now causes the request of the Credit1 scheduler to be honoured
> (rather than giving us Credit2), but take this opportunity to switch to Null,
> as the previously problematic issues are now believed to be fixed.
> 
> Enabling EXPERT also allows XEN_SHSTK to be selected, and we don't want this
> being built for shim.  We also don't want TRACEBUFFER or GDBSX either.
> 
> Take this oppotunity to swap the disable of HVM_FEP for a general disable of
> HVM (likely to have wider impliciations in the future), and disable ARGO (will
> necesserily need plumbing work to function in shim).

Odd. I was quite sure this is the case already; in particular my
own build test of a shim config has this already.

> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

I have a question though (without implying the patch here needs
adjusting, but rather with a look towards after 4.14):

> --- a/xen/arch/x86/configs/pvshim_defconfig
> +++ b/xen/arch/x86/configs/pvshim_defconfig
> @@ -5,19 +5,25 @@ CONFIG_PVH_GUEST=y
>  CONFIG_PV_SHIM=y
>  CONFIG_PV_SHIM_EXCLUSIVE=y
>  CONFIG_NR_CPUS=32
> +CONFIG_EXPERT=y
> +CONFIG_SCHED_NULL=y
>  # Disable features not used by the PV shim
> +# CONFIG_HVM is not set
> +# CONFIG_XEN_SHSTK is not set
>  # CONFIG_HYPFS is not set
>  # CONFIG_SHADOW_PAGING is not set
>  # CONFIG_BIGMEM is not set
> -# CONFIG_HVM_FEP is not set
>  # CONFIG_TBOOT is not set
>  # CONFIG_KEXEC is not set
>  # CONFIG_XENOPROF is not set
>  # CONFIG_XSM is not set
> +# CONFIG_ARGO is not set
> +# CONFIG_SCHED_CREDIT is not set
>  # CONFIG_SCHED_CREDIT2 is not set
>  # CONFIG_SCHED_RTDS is not set
>  # CONFIG_SCHED_ARINC653 is not set
> -# CONFIG_SCHED_NULL is not set
>  # CONFIG_LIVEPATCH is not set
>  # CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS is not set
> +# CONFIG_TRACEBUFFER is not set
>  # CONFIG_DEBUG is not set
> +# CONFIG_GDBSX is not set

I assume both the "enable" and "disable" sections here are ordered
like they would be in a resulting full .config. But this being two
separate sections, doing so doesn't help e.g. diff-ing. How about
we sort both sections alphabetically (short of other good sorting
criteria, yet better than entirely unsorted)?

Jan