Hi Arnaldo,
On Tue, 2015-07-14 at 10:46 -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jul 13, 2015 at 11:24:06PM +0300, Aaro Koskinen escreveu:
> > Hi,
> >
> > On Mon, Jul 13, 2015 at 02:10:53PM +0300, Alexey Brodkin wrote:
> > > This reverts commit 5ef7bbb09f7b
> > > ("perf tools: Allow to specify custom linker command").
> > >
> > > LD is a pre-defined variable in GNU Make. I.e. it is always defined.
> > > Which means there's no point to check "LD ?= ..." because it will never
> > > succeed. And so LD will be either that explicitly passed to make like
> > > this:
> > > ------->8-------
> > > make LD=path_to_my_ld ...
> > > ------->8-------
> > > or default value, which is host's "ld".
> > >
> > > Latter leads to failure of cross-linkage because instead of cross linker
> > > "$(CROSS_COMPILE)ld" host's "ld" is used.
> > >
> > > As for commit which is reverted here:
> > > [1] Usually for selection of non-default flavour of CPU core/options
> > > linker flags are used like "-mtune=xxx" or "-mMyCPUType" etc.
> > >
> > > [2] Still to implement ability to use "ld" that differs from
> > > "$(CROSS_COMPILE)ld" one will need to add new makefile variable like
> > > TARGET_LD and then check if $(TARGET_LD) is not specified on make
> > > invocation then use "$(CROSS_COMPILE)ld".
> > >
> > > But for now to fix cross-building of perf this revert is enough.
> >
> > Hmm. You are probably right, my build system always exports LD with
> > correct linker for cross builds so perhaps that's why I this "worked"
> > for me when testing. Sorry.
>
> So, I think this is an "Acked-by: Aaro Koskinen <aaro.koski...@iki.fi>"
> for the revert, right?
>
> > I guess the correct fix would be [1], i.e. there should be some new
> > variable to pass flags to ld command.
> >
> > Or maybe [2], could we use make "origin" function? If LD is "default",
> > then use "$(CROSS_COMPILE)ld", otherwise use what the user passed?
>
> When you guys get to some conclusion, please submit a new patch, for now
> I am taking the revert with the (implied) Acked-by Aaro, ok?
Please find my patch that both reverts initial Aaro's patch and implements
proper handling of CC, AR and LD substitution here -
https://lkml.org/lkml/2015/7/14/149
-Alexey--
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