On 17/02/2020 22:39, Ard Biesheuvel wrote:

On Mon, 17 Feb 2020 at 17:46, Will Deacon [off-list ref] wrote:

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On Mon, Feb 17, 2020 at 12:26:16PM +0000, Vincenzo Frascino wrote:

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On 13/02/2020 18:44, Nathan Chancellor wrote:

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On Thu, Feb 13, 2020 at 04:16:14PM +0000, Vincenzo Frascino wrote:

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Enable Clang Compilation for the vdso32 library.

[...]

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+LD_COMPAT ?= $(CROSS_COMPILE_COMPAT)gcc

Well this is unfortunate :/

It looks like adding the --target flag to VDSO_LDFLAGS allows
clang to link the vDSO just fine although it does warn that -nostdinc
is unused:

clang-11: warning: argument unused during compilation: '-nostdinc'
[-Wunused-command-line-argument]

This is why ended up in this "unfortunate" situation :) I wanted to avoid the
warning.

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It would be nice if the logic of commit fe00e50b2db8 ("ARM: 8858/1:
vdso: use $(LD) instead of $(CC) to link VDSO") could be adopted here
but I get that this Makefile is its own beast :) at the very least, I
think that the --target flag should be added to VDSO_LDFLAGS so that gcc
is not a requirement for this but I am curious if you tried that already
and noticed any issues with it.

--target is my preferred way as well, I can try to play another little bit with
the flags and see what I can come up with in the next version.

Yes, please. I'd even prefer the warning rather than silently assuming that
a cross gcc is kicking around on the path.

Doesn't Clang have -Qunused-arguments for that?

Yes, this is exactly what I was looking for. Thanks Ard :)

-- 
Regards,
Vincenzo