Re: [Xen-devel] [PATCH 01/12] xen: clang: Support correctly cross-compile

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 29 Mar 2019, Jan Beulich wrote:
> >>> On 29.03.19 at 10:41, <julien.grall@xxxxxxx> wrote:
> > On 28/03/2019 09:55, Jan Beulich wrote:
> >>>>> On 27.03.19 at 19:45, <julien.grall@xxxxxxx> wrote:
> >>> Clang uses "-target" option for cross-compilation.
> >> 
> >>> --- a/config/StdGNU.mk
> >>> +++ b/config/StdGNU.mk
> >>> @@ -1,8 +1,13 @@
> >>>   AS         = $(CROSS_COMPILE)as
> >>>   LD         = $(CROSS_COMPILE)ld
> >>>   ifeq ($(clang),y)
> >>> -CC         = $(CROSS_COMPILE)clang
> >>> -CXX        = $(CROSS_COMPILE)clang++
> >>> +ifneq ($(CROSS_COMPILE),)
> >>> +CC         = clang -target $(CROSS_COMPILE:-=)
> >>> +CXX        = clang++ -target $(CROSS_COMPILE:-=)
> >> 
> >> Is dropping dashes from the variable uniformly correct? If so,
> >> could you please clarify in the commit message why that is?
> > The target option requires the following format:
> > 
> > <arch><sub>-<vendor>-<sys>-<abi>
> > 
> > In other places, we need the trailing dash as GNU tools are using the same 
> > format as above with a dash to separate the tool name.
> 
> Oh, I'm sorry - I keep forgetting that the substitution form you
> use only fiddles with trailing dashes. Of course I won't insist, but
> I'd prefer the more obvious $(patsubst %-,%,$(CROSS_COMPILE))
> to be used instead, despite realizing that it's meaningfully longer.

Either way to do variable manipulation is OK, but it would be good to
add Julien's explanation of the -target expected format in the commit
message. I don't have any other comments on this patch.

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