Re: [Qemu-devel] [PATCH qemu] configure/fdt: Use more strict test for libfdt version

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Nov 15, 2018 at 10:11:12AM +0000, Daniel P. Berrangé wrote:
> On Thu, Nov 15, 2018 at 02:56:59PM +1100, Alexey Kardashevskiy wrote:
> > The libfdt installed in the system is preferred to the dtc submodule by
> > default. The recent libfdt update added a new symbol - fdt_check_full -
> > and this breaks compile if there is an older libfdt installed in
> > the system.
> 
> Unless I'm missing something, QEMU doesn't use the fdt_check_full symbol,
> so why would the lack of this symbol cause a compile failure. 
> 
> It should be fine if the dtc submodule contains a newer libfdt than the
> host system. As long as QEMU doesn't actually need any of the APIs in
> the newer libfdt we should be able to continue using the older system
> version if it is present.
> 
> Could you elaborate on what build problems you are having.
> 
> > This changes the test to force ./configure into using newer libfdt.
> 
> I'm not convinced we want todo that.

So I think the point here is that Alexey has some other outstanding
patches that will use fdt_check_full().  The commit message needs to
make that clear though.  Or else include this patch in that series.

> 
> > 
> > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > ---
> >  configure | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/configure b/configure
> > index 74e313a..7e16a6c 100755
> > --- a/configure
> > +++ b/configure
> > @@ -3826,7 +3826,7 @@ if test "$fdt" != "no" ; then
> >    cat > $TMPC << EOF
> >  #include <libfdt.h>
> >  #include <libfdt_env.h>
> > -int main(void) { fdt_first_subnode(0, 0); return 0; }
> > +int main(void) { fdt_check_full(NULL, 0); return 0; }
> >  EOF
> >    if compile_prog "" "$fdt_libs" ; then
> >      # system DTC is good - use it
> 
> Regards,
> Daniel

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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