Hi Philippe,
On 9/8/20 9:56 AM, Philippe Mathieu-Daudé wrote:
> +Laurent
>
> On 9/8/20 9:09 AM, Claudio Fontana wrote:
>> On 9/7/20 6:49 PM, Philippe Mathieu-Daudé wrote:
>>> On 9/7/20 6:30 PM, Claudio Fontana wrote:
>>>> On 9/7/20 12:20 PM, Philippe Mathieu-Daudé wrote:
>>>>> On 9/7/20 12:05 PM, Claudio Fontana wrote:
>>>>>> Hi Richard,
>>>>>>
>>>>>> currently rebasing on top of this one,
>>>>>> just a question, why is the patch not directly using "current_machine"?
>>>>>
>>>>> For user mode?
>>>>
>>>> In user mode I'd not expect softmmu/cpus.c to be built at all...
>>>
>>> Which is why :) current_machine is NULL in user-mode.
>>
>> Ciao Philippe,
>>
>> then why does the patch change softmmu/cpus.c in a way that accounts for
>> user mode?
>>
>> The function that the patch changes is never called in user mode.
>>
>> The patch could instead use current_machine without any concern of it being
>> NULL, it will always be set in vl.c .
>
> Better send a patch to prove your point :)
Yes, I am already testing without problems the cpus-refactoring series with
this applied:
commit 53f6db772f1522025650441102b16be17773bdc9
Author: Claudio Fontana <cfont...@suse.de>
Date: Tue Sep 8 10:59:07 2020 +0200
accel/tcg: use current_machine as it is always set for softmmu
current_machine is always set before accelerators are initialized,
so use that instead of MACHINE(qdev_get_machine()).
Signed-off-by: Claudio Fontana <cfont...@suse.de>
diff --git a/accel/tcg/tcg-cpus.c b/accel/tcg/tcg-cpus.c
index ec7158b55e..05af1168a2 100644
--- a/accel/tcg/tcg-cpus.c
+++ b/accel/tcg/tcg-cpus.c
@@ -484,7 +484,7 @@ static void tcg_start_vcpu_thread(CPUState *cpu)
* then we will have cpus running in parallel.
*/
if (qemu_tcg_mttcg_enabled()) {
- MachineState *ms = MACHINE(qdev_get_machine());
+ MachineState *ms = current_machine;
if (ms->smp.max_cpus > 1) {
parallel_cpus = true;
}
>
> I have bad remember about the last time I tried to understand/modify
> that part, because IIRC the user-mode creates some fake machine to
> satisfy various QEMU generic code assumptions. Sincerely I now prefer
> stay away from this; too many unmerged patches there.
linux-user/main.c and bsd-user/main.c seem to use cpu_create() to create the
cpus,
then they have their own cpu_loop(), they do not use any of the cpus.c code.
By contrast, softmmu/vl.c initializes current_machine in qemu_init(),
even before accelerator is chosen and configured.
So there is no chance currently that current_machine is not set correctly when
the accelerator vcpu startup code in is called.
Ciao,
CLaudio
>
>>
>> Ciao,
>>
>> Claudio
>>
>>>
>>>>
>>>> Ciao,
>>>>
>>>> Claudio
>>>>
>>>>>
>>>>>>
>>>>>> Is using MACHINE(qdev_get_machine()) preferrable here?
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Claudio
>>>>>>
>>>>>> On 9/3/20 11:40 PM, Richard Henderson wrote:
>>>>>>> Do not set parallel_cpus if there is only one cpu instantiated.
>>>>>>> This will allow tcg to use serial code to implement atomics.
>>>>>>>
>>>>>>> Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
>>>>>>> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
>>>>>>> ---
>>>>>>> softmmu/cpus.c | 11 ++++++++++-
>>>>>>> 1 file changed, 10 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/softmmu/cpus.c b/softmmu/cpus.c
>>>>>>> index a802e899ab..e3b98065c9 100644
>>>>>>> --- a/softmmu/cpus.c
>>>>>>> +++ b/softmmu/cpus.c
>>>>>>> @@ -1895,6 +1895,16 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
>>>>>>> if (!tcg_region_inited) {
>>>>>>> tcg_region_inited = 1;
>>>>>>> tcg_region_init();
>>>>>>> + /*
>>>>>>> + * If MTTCG, and we will create multiple cpus,
>>>>>>> + * then we will have cpus running in parallel.
>>>>>>> + */
>>>>>>> + if (qemu_tcg_mttcg_enabled()) {
>>>>>>> + MachineState *ms = MACHINE(qdev_get_machine());
>>>>>>
>>>>>> MachineState *ms = current_machine;
>>>>>> ?
>>>>>>
>>>>>>
>>>>>>> + if (ms->smp.max_cpus > 1) {
>>>>>>> + parallel_cpus = true;
>>>>>>> + }
>>>>>>> + }
>>>>>>> }
>>>>>>>
>>>>>>> if (qemu_tcg_mttcg_enabled() || !single_tcg_cpu_thread) {
>>>>>>> @@ -1904,7 +1914,6 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
>>>>>>>
>>>>>>> if (qemu_tcg_mttcg_enabled()) {
>>>>>>> /* create a thread per vCPU with TCG (MTTCG) */
>>>>>>> - parallel_cpus = true;
>>>>>>> snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
>>>>>>> cpu->cpu_index);
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>
>>>>
>>
>>
