Re: [PATCH 03/32] vdso.7: Remove outdated limitation for powerpc

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

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.)

> [
> 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.

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



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/