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

[Markus Armbruster]

Greg Kurz <address@hidden> writes:

> On Wed, 6 Nov 2019 14:01:01 +0100
> Laurent Vivier <address@hidden> 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 <address@hidden>
>> > ---
>> >  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. <===

You're right.

Since I have nothing queued up right now, I'd prefer to have this go via
qemu-trivial.

> 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.