Re: [Qemu-devel] [PATCH v8 14/14] target: Use qemu_log() instead of fprintf(stderr, ...)

[Alistair Francis <alistair.francis@xilinx.com>]

On Mon, Feb 5, 2018 at 6:31 AM, Markus Armbruster <armbru@redhat.com> wrote:
> Thomas Huth <thuth@redhat.com> writes:
>
>> On 05.02.2018 07:33, Markus Armbruster wrote:
>>> Thomas Huth <thuth@redhat.com> writes:
>>>
>>>> On 03.02.2018 09:43, Markus Armbruster wrote:
>>>>> From: Alistair Francis <alistair.francis@xilinx.com>
>>>>>
>>>>> Convert fprintf(stderr, ...) to use qemu_log(). Double prints in
>>>>> target/ppc/translate.c were manually remove. A fprintf() in
>>>>> target/sh4/translate.c was kept as it's inside a #if 0. The #if 0 and
>>>>> fflush() was removed around the unimplemented log in
>>>>> target/sh4/translate.c as well.
>>>>>
>>>>> Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
>>>>> [Trivial conflict with 6f1c2af641d resolved]
>>>>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>>>>> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>>>>> ---
>>>>>  target/cris/translate.c      |  2 +-
>>>>>  target/ppc/translate.c       | 36 ++++++++++--------------------------
>>>>>  target/sh4/translate.c       |  7 ++-----
>>>>>  target/unicore32/translate.c |  2 +-
>>>>>  4 files changed, 14 insertions(+), 33 deletions(-)
>>>>>
>>>>> diff --git a/target/cris/translate.c b/target/cris/translate.c
>>>>> index f51a731db9..ff31311ed0 100644
>>>>> --- a/target/cris/translate.c
>>>>> +++ b/target/cris/translate.c
>>>>> @@ -137,7 +137,7 @@ typedef struct DisasContext {
>>>>>
>>>>>  static void gen_BUG(DisasContext *dc, const char *file, int line)
>>>>>  {
>>>>> -    fprintf(stderr, "BUG: pc=%x %s %d\n", dc->pc, file, line);
>>>>> +    qemu_log("BUG: pc=%x %s %d\n", dc->pc, file, line);
>>>>>      if (qemu_log_separate()) {
>>>>>          qemu_log("BUG: pc=%x %s %d\n", dc->pc, file, line);
>>>>>      }
>>>>
>>>> This one is still logging twice now.
>>>
>>> Hmm.
>>>
>>>>> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
>>>>> index 4132f67bb1..172c9f2001 100644
>>>>> --- a/target/ppc/translate.c
>>>>> +++ b/target/ppc/translate.c
>>>>> @@ -3933,12 +3933,8 @@ static inline void gen_op_mfspr(DisasContext *ctx)
>>>>>               * allowing userland application to read the PVR
>>>>>               */
>>>>>              if (sprn != SPR_PVR) {
>>>>> -                fprintf(stderr, "Trying to read privileged spr %d (0x%03x) at "
>>>>> -                        TARGET_FMT_lx "\n", sprn, sprn, ctx->nip - 4);
>>>>> -                if (qemu_log_separate()) {
>>>>> -                    qemu_log("Trying to read privileged spr %d (0x%03x) at "
>>>>> -                             TARGET_FMT_lx "\n", sprn, sprn, ctx->nip - 4);
>>>>> -                }
>>>>> +                qemu_log("Trying to read privileged spr %d (0x%03x) at "
>>>>> +                         TARGET_FMT_lx "\n", sprn, sprn, ctx->nip - 4);
>>>>
>>>> I wonder whether that should maybe rather be a
>>>> qemu_log_mask(LOG_GUEST_ERROR, ...) instead? Well, but maybe that's
>>>> subject to another patch...
>>>
>>> qemu_log_separate() appears to be always used like this
>>>
>>>     fprintf(stderr, ... the message ...);
>>>     if (qemu_log_separate()) {
>>>         qemu_log(... the same message ...);
>>>     }
>>>
>>> Are you proposing to replace this pattern by
>>>
>>>     qemu_log_mask(LOG_GUEST_ERROR, ...the message ...);
>>>
>>> ?
>>
>> Not globally, only in target/ppc/translate.c. The wrong accesses to SPR
>> (special purpose registers) there indicate that the guest has likely
>> tried to do something wrong.
>>
>> Globally, I wonder whether it still makes sense to keep the
>> qemu_log_separate() stuff - we rather want to get rid of all fprintfs,
>> don't we?
>
> The qemu_log_separate() pattern feels wrong to me.  If we have a class
> of messages that should go to stderr in addition to the log (unless the
> two are the same), then we should have a log level / mask / function /
> whatever to do that.
>
> To expedite merging of the rest of the series, I'll drop this patch from
> it.
>
> Alistair, would you be willing to work with Thomas to revise this patch?

Yeah, I'm happy to.

What do we think then? Just swap to qemu_log_mask() and
error_report()? Or do we need something more?

Alistair

>