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Re: [PATCH 1/7] qemu-common: Briefly document qemu_timedate_diff() unit
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH 1/7] qemu-common: Briefly document qemu_timedate_diff() unit |
Date: |
Mon, 22 Jun 2020 10:50:53 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 6/18/20 7:47 AM, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <f4bug@amsat.org> writes:
>
>> It is not obvious that the qemu_timedate_diff() and
>> qemu_ref_timedate() functions return seconds. Briefly
>> document it.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>> include/qemu-common.h | 1 +
>> softmmu/vl.c | 2 +-
>> 2 files changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/qemu-common.h b/include/qemu-common.h
>> index d0142f29ac..e97644710c 100644
>> --- a/include/qemu-common.h
>> +++ b/include/qemu-common.h
>> @@ -27,6 +27,7 @@ int qemu_main(int argc, char **argv, char **envp);
>> #endif
>>
>> void qemu_get_timedate(struct tm *tm, int offset);
>> +/* Returns difference with RTC reference time (in seconds) */
>> int qemu_timedate_diff(struct tm *tm);
>
> Not this patch's problem: use of int here smells; is it wide enough?
I'll add a /* FIXME */ comment.
>
>>
>> void *qemu_oom_check(void *ptr);
>> diff --git a/softmmu/vl.c b/softmmu/vl.c
>> index f669c06ede..215459c7b5 100644
>> --- a/softmmu/vl.c
>> +++ b/softmmu/vl.c
>> @@ -737,7 +737,7 @@ void qemu_system_vmstop_request(RunState state)
>> }
>>
>> /***********************************************************/
>> -/* RTC reference time/date access */
>> +/* RTC reference time/date access (in seconds) */
>> static time_t qemu_ref_timedate(QEMUClockType clock)
>> {
>> time_t value = qemu_clock_get_ms(clock) / 1000;
>
> time_t is seconds on all systems we support. Using it for something
> other than seconds would be wrong. The comment feels redundant to me.
> But if it helps someone else...
Ah, TIL 'time_t' is the arithmetic time type to represent
the number of seconds since the epoch.
I guess I almost never used it ... (Not something real time
embedded systems care much) :)
So scratch that comment.
>
>
- [PATCH 0/7] misc: Reduce QEMUTimer pressure by using lower precision when possible, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 1/7] qemu-common: Briefly document qemu_timedate_diff() unit, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 2/7] block/qcow2: Document cache_clean_interval field holds seconds, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 3/7] block/curl: Reduce timer precision to milli-second, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 4/7] hw/virtio/virtio-balloon: Rename timer field including 'ms' unit, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 5/7] hw/rtc/m48t59: Reduce timer precision to milli-second, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 6/7] hw/ipmi/ipmi_bmc_extern: Reduce timer precision to milli-second, Philippe Mathieu-Daudé, 2020/06/16
- [PATCH 7/7] hw/watchdog/wdt_aspeed: Reduce timer precision to micro-second, Philippe Mathieu-Daudé, 2020/06/16