Re: [PATCH] arch/x86/purgatory/Makefile: supress kexec-purgatory.c is up to date message

From: WANG Chao
Date: Tue Oct 14 2014 - 22:14:52 EST


On 10/14/14 at 05:52pm, Vivek Goyal wrote:
> On Tue, Oct 14, 2014 at 12:46:58PM +0800, WANG Chao wrote:
> > Supress this unnecessary message during kernel re-build
> > (CONFIG_KEXEC_FILE=y):
> >
> > make[1]: `arch/x86/purgatory/kexec-purgatory.c' is up to date.
> >
> > Signed-off-by: WANG Chao <chaowang@xxxxxxxxxx>
> > ---
> > arch/x86/purgatory/Makefile | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
> > index f52e033..2c835e3 100644
> > --- a/arch/x86/purgatory/Makefile
> > +++ b/arch/x86/purgatory/Makefile
> > @@ -24,6 +24,7 @@ quiet_cmd_bin2c = BIN2C $@
> >
> > $(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
> > $(call if_changed,bin2c)
> > + @:
>
> Where can I find the description of "@:" and how does it work?

@ is used to suppress echo'ing. See:
https://www.gnu.org/software/make/manual/html_node/Echoing.html

This is a trick to avoid "... is up to date" message". Check out commit
a9358bc ("x86/build: Supress realmode.bin is up to date message").

Thanks
WANG Chao
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