Re: [PATCH] numa: Add missing \n to error message

[Greg Kurz <groug@kaod.org>]

On Wed, 6 Nov 2019 14:01:01 +0100
Laurent Vivier <laurent@vivier.eu> wrote:

> Le 06/11/2019 à 13:46, Greg Kurz a écrit :
> > If memory allocation fails when using -mem-path, QEMU is supposed to print
> > out a message to indicate that fallback to anonymous RAM is deprecated. This
> > is done with error_printf() which does output buffering. As a consequence,
> > the message is only printed at the next flush, eg. when quiting QEMU, and
> > it also lacks a trailing newline:
> > 
> > qemu-system-ppc64: unable to map backing store for guest RAM: Cannot allocate memory
> > qemu-system-ppc64: warning: falling back to regular RAM allocation
> > QEMU 4.1.50 monitor - type 'help' for more information
> > (qemu) q
> > This is deprecated. Make sure that -mem-path  specified path has sufficient resources to allocate -m specified RAM amountgreg@boss02:~/Work/qemu/qemu-spapr$
> > 
> > Add the missing \n to fix both issues.
> > 
> > Fixes: cb79224b7e4b "deprecate -mem-path fallback to anonymous RAM"
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> >  hw/core/numa.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/hw/core/numa.c b/hw/core/numa.c
> > index 038c96d4abc6..e3332a984f7c 100644
> > --- a/hw/core/numa.c
> > +++ b/hw/core/numa.c
> > @@ -503,7 +503,7 @@ static void allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner,
> >              warn_report("falling back to regular RAM allocation");
> >              error_printf("This is deprecated. Make sure that -mem-path "
> >                           " specified path has sufficient resources to allocate"
> > -                         " -m specified RAM amount");
> > +                         " -m specified RAM amount\n");
> >              /* Legacy behavior: if allocation failed, fall back to
> >               * regular RAM allocation.
> >               */
> > 
> > 
> 
> Why is this an error_printf() and not an error_report()?
> 

Because CODING_STYLE suggests to do so I guess:

Reporting errors to the human user
----------------------------------

Do not use printf(), fprintf() or monitor_printf().  Instead, use
error_report() or error_vreport() from error-report.h.  This ensures the
error is reported in the right place (current monitor or stderr), and in
a uniform format.

Use error_printf() & friends to print additional information. <===

error_report() prints the current location.  In certain common cases
like command line parsing, the current location is tracked
automatically.  To manipulate it manually, use the loc_``*``() from
error-report.h.

> Thanks,
> Laurent
>