Re: [PATCH 03/32] vdso.7: Remove outdated limitation for powerpc

["Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>]

Hello Michael,

On 8/8/21 2:17 AM, Michael Kerrisk (man-pages) wrote:
> Hello Alex,
> 
> On 7/28/21 10:19 PM, Alejandro Colomar wrote:
>> Christophe Leroy via Bugzilla:
> 
> For the commit message, it would be good to have a URL for 
> the bug. (I could not find the bug.)

That's right.  <https://bugzilla.kernel.org/show_bug.cgi?id=213419>

> 
>> [
>> https://man7.org/linux/man-pages/man7/vdso.7.html
>> (as of today, flagged 2021-03-22)
>>
>> ppc/32 and ppc/64 sections both have the following note:
>>
>>        The CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE clocks
>>        are not supported by the __kernel_clock_getres and
>>        __kernel_clock_gettime interfaces; the kernel falls back to
>>        the real system call
>>
>> This note has been wrong from quite some time now,
>> since commit 654abc69ef2e
>> ("powerpc/vdso32: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE")
>> and commit 5c929885f1bb
>> ("powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE")
>> ]
>>
>> Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
> 
> In cases such as this, I prefer not to drop the historical info.
> See below.

And also right.

> 
>> ---
>>  man7/vdso.7 | 26 --------------------------
>>  1 file changed, 26 deletions(-)
>>
>> diff --git a/man7/vdso.7 b/man7/vdso.7
>> index ef6bef5bd..1d527c38e 100644
>> --- a/man7/vdso.7
>> +++ b/man7/vdso.7
>> @@ -385,19 +385,6 @@ __kernel_sync_dicache_p5	LINUX_2.6.15
>>  .in
>>  .ft P
>>  \}
>> -.PP
>> -The
>> -.B CLOCK_REALTIME_COARSE
>> -and
>> -.B CLOCK_MONOTONIC_COARSE
>> -clocks are
>> -.I not
>> -supported by the
>> -.I __kernel_clock_getres
>> -and
>> -.I __kernel_clock_gettime
>> -interfaces;
>> -the kernel falls back to the real system call.
>>  .SS ppc/64 functions
>>  .\" See linux/arch/powerpc/kernel/vdso64/vdso64.lds.S
>>  The table below lists the symbols exported by the vDSO.
>> @@ -423,19 +410,6 @@ __kernel_sync_dicache_p5	LINUX_2.6.15
>>  .in
>>  .ft P
>>  \}
>> -.PP
>> -The
>> -.B CLOCK_REALTIME_COARSE
>> -and
>> -.B CLOCK_MONOTONIC_COARSE
>> -clocks are
>> -.I not
>> -supported by the
>> -.I __kernel_clock_getres
>> -and
>> -.I __kernel_clock_gettime
>> -interfaces;
>> -the kernel falls back to the real system call.
>>  .SS riscv functions
>>  .\" See linux/arch/riscv/kernel/vdso/vdso.lds.S
>>  The table below lists the symbols exported by the vDSO.
> 
> I instead applied the patch below.
> 
> Cheers,
> 
> Michael
> 
> 
> diff --git a/man7/vdso.7 b/man7/vdso.7
> index ef6bef5bd..39d6dc4ad 100644
> --- a/man7/vdso.7
> +++ b/man7/vdso.7
> @@ -386,7 +386,9 @@ __kernel_sync_dicache_p5    LINUX_2.6.15
>  .ft P
>  \}
>  .PP
> -The
> +In kernel versions before Linux 5.6,
> +.\" commit 654abc69ef2e69712e6d4e8a6cb9292b97a4aa39
> +the
>  .B CLOCK_REALTIME_COARSE
>  and
>  .B CLOCK_MONOTONIC_COARSE
> @@ -424,7 +426,9 @@ __kernel_sync_dicache_p5    LINUX_2.6.15
>  .ft P
>  \}
>  .PP
> -The
> +In kernel versions before Linux 4.16,
> +.\" commit 5c929885f1bb4b77f85b1769c49405a0e0f154a1
> +the

Much better!

Thanks,

Alex

>  .B CLOCK_REALTIME_COARSE
>  and
>  .B CLOCK_MONOTONIC_COARSE
> 
> 
> 

-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/