Qemu wraps its call to ninja in a Makefile. Since ninja, as opposed to
make, utilizes all CPU cores by default, the qemu Makefile translates
the absense of a `-jN` argument into `-j1`. This breaks jobserver
functionality, so update the -jN mangling to take the --jobserver-auth
argument into considerationa too.

Signed-off-by: Martin Hundebøll <martin@geanix.com>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 8f36990335..183756018f 100644
--- a/Makefile
+++ b/Makefile
@@ -142,7 +142,7 @@ MAKE.k = $(findstring k,$(firstword $(filter-out --%,$(MAKEFLAGS))))
 MAKE.q = $(findstring q,$(firstword $(filter-out --%,$(MAKEFLAGS))))
 MAKE.nq = $(if $(word 2, $(MAKE.n) $(MAKE.q)),nq)
 NINJAFLAGS = $(if $V,-v) $(if $(MAKE.n), -n) $(if $(MAKE.k), -k0) \
-        $(filter-out -j, $(lastword -j1 $(filter -l% -j%, $(MAKEFLAGS)))) \
+        $(or $(filter -l% -j%, $(MAKEFLAGS)), $(if $(filter --jobserver-auth=%, $(MAKEFLAGS)),, -j1)) \
         -d keepdepfile
 ninja-cmd-goals = $(or $(MAKECMDGOALS), all)
 ninja-cmd-goals += $(foreach g, $(MAKECMDGOALS), $(.ninja-goals.$g))
-- 
2.44.0

Am 02.04.24 um 10:17 schrieb Martin Hundebøll:
> Qemu wraps its call to ninja in a Makefile. Since ninja, as opposed to
> make, utilizes all CPU cores by default, the qemu Makefile translates
> the absense of a `-jN` argument into `-j1`. This breaks jobserver
> functionality, so update the -jN mangling to take the --jobserver-auth
> argument into considerationa too.
> 
> Signed-off-by: Martin Hundebøll <martin@geanix.com>
> ---
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index 8f36990335..183756018f 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -142,7 +142,7 @@ MAKE.k = $(findstring k,$(firstword $(filter-out --%,$(MAKEFLAGS))))
>  MAKE.q = $(findstring q,$(firstword $(filter-out --%,$(MAKEFLAGS))))
>  MAKE.nq = $(if $(word 2, $(MAKE.n) $(MAKE.q)),nq)
>  NINJAFLAGS = $(if $V,-v) $(if $(MAKE.n), -n) $(if $(MAKE.k), -k0) \
> -        $(filter-out -j, $(lastword -j1 $(filter -l% -j%, $(MAKEFLAGS)))) \
> +        $(or $(filter -l% -j%, $(MAKEFLAGS)), $(if $(filter --jobserver-auth=%, $(MAKEFLAGS)),, -j1)) \
>          -d keepdepfile
>  ninja-cmd-goals = $(or $(MAKECMDGOALS), all)
>  ninja-cmd-goals += $(foreach g, $(MAKECMDGOALS), $(.ninja-goals.$g))

Hi,

unfortunately, this patch breaks build when specifying just '-j' as a
make flag (i.e. without a number), because it will now end up being
passed to ninja:

> $ make -j
> changing dir to build for make ""...
> make[1]: Entering directory '/home/febner/repos/qemu/build'
> ninja: fatal: invalid -j parameter

Best Regards,
Fiona

On Fri, Apr 12, 2024 at 1:52 PM Fiona Ebner <f.ebner@proxmox.com> wrote:
>
> Am 02.04.24 um 10:17 schrieb Martin Hundebøll:
> > Qemu wraps its call to ninja in a Makefile. Since ninja, as opposed to
> > make, utilizes all CPU cores by default, the qemu Makefile translates
> > the absense of a `-jN` argument into `-j1`. This breaks jobserver
> > functionality, so update the -jN mangling to take the --jobserver-auth
> > argument into considerationa too.
> >
> > Signed-off-by: Martin Hundebøll <martin@geanix.com>
> > ---
> >  Makefile | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 8f36990335..183756018f 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -142,7 +142,7 @@ MAKE.k = $(findstring k,$(firstword $(filter-out --%,$(MAKEFLAGS))))
> >  MAKE.q = $(findstring q,$(firstword $(filter-out --%,$(MAKEFLAGS))))
> >  MAKE.nq = $(if $(word 2, $(MAKE.n) $(MAKE.q)),nq)
> >  NINJAFLAGS = $(if $V,-v) $(if $(MAKE.n), -n) $(if $(MAKE.k), -k0) \
> > -        $(filter-out -j, $(lastword -j1 $(filter -l% -j%, $(MAKEFLAGS)))) \
> > +        $(or $(filter -l% -j%, $(MAKEFLAGS)), $(if $(filter --jobserver-auth=%, $(MAKEFLAGS)),, -j1)) \
> >          -d keepdepfile
> >  ninja-cmd-goals = $(or $(MAKECMDGOALS), all)
> >  ninja-cmd-goals += $(foreach g, $(MAKECMDGOALS), $(.ninja-goals.$g))
>
> Hi,
>
> unfortunately, this patch breaks build when specifying just '-j' as a
> make flag (i.e. without a number), because it will now end up being
> passed to ninja:

Yep, I've sent a pull request with the fix.

Paolo

Queued, thanks.

Paolo