Re: [RFC PATCH glibc v3] mach: Add CLOCK_MONOTONIC case in clock_gettime()

[Samuel Thibault]

Hello,

Zhaoming Luo, le lun. 06 janv. 2025 12:39:07 +0800, a ecrit:
> mach: Add CLOCK_MONOTONIC case in clock_gettime()
> 
> The Mach RPC host_get_uptime64() is implemented. It returns the elapsed time
> value since bootup. See
> 
> https://git.savannah.gnu.org/cgit/hurd/gnumach.git/commit/?id=fc494bfe3fb6363e1077dc035eb119970d84a9d1
> 
> In this patch, the RPC is used to implement the monotonic clock for
> mach.
> 
> * config.h.in: Add HAVE_HOST_GET_UPTIME64 config entry
> * sysdeps/mach/clock_gettime.c: Add CLOCK_MONOTONIC case
> * sysdeps/mach/configure: Check the existence of host_get_uptime64 RPC
> * sysdeps/mach/configure.ac: Check the existence of host_get_uptime64 RPC
> 
> ---
>  config.h.in                  |  3 +++
>  sysdeps/mach/clock_gettime.c | 25 +++++++++++++++++++++++++
>  sysdeps/mach/configure       | 30 ++++++++++++++++++++++++++++++
>  sysdeps/mach/configure.ac    |  2 ++
>  4 files changed, 60 insertions(+)
> 
> diff --git a/config.h.in b/config.h.in
> index c26f98ccd6..cdbd555366 100644
> --- a/config.h.in
> +++ b/config.h.in
> @@ -163,6 +163,9 @@
>  /* Mach specific: define if the `host_page_size' RPC is available.  */
>  #undef       HAVE_HOST_PAGE_SIZE
>  
> +/* Mach specific: define if the `host_get_uptime64' RPC is available.  */
> +#undef       HAVE_HOST_GET_UPTIME64
> +
>  /* Mach specific: define if the `thread_set_name' RPC is available.  */
>  #undef  HAVE_MACH_THREAD_SET_NAME
>  
> diff --git a/sysdeps/mach/clock_gettime.c b/sysdeps/mach/clock_gettime.c
> index 6fffad39f5..b29acab908 100644
> --- a/sysdeps/mach/clock_gettime.c
> +++ b/sysdeps/mach/clock_gettime.c
> @@ -20,6 +20,7 @@
>  #include <mach.h>
>  #include <assert.h>
>  #include <shlib-compat.h>
> +#include <mach/mig_errors.h>
>  
>  /* Get the current time of day, putting it into *TS.
>     Returns 0 on success, -1 on errors.  */
> @@ -31,6 +32,30 @@ __clock_gettime (clockid_t clock_id, struct timespec *ts)
>  
>    switch (clock_id) {
>  
> +    case CLOCK_MONOTONIC:
> +/* If HAVE_HOST_GET_UPTIME64 is not defined, CLOCK_MONOTONIC will be 
> equivalent
> +   to CLOCK_REALTIME.  */
> +#ifdef HAVE_HOST_GET_UPTIME64
> +      {
> +     time_value64_t tv;
> +     err = __host_get_uptime64 (__mach_host_self (), &tv);
> +
> +     if (err)
> +       {
> +         if (err == MIG_BAD_ID)
> +           {
> +             /* Not supported by the running kernel.  */
> +             __set_errno (EINVAL);

I changed this a bit to fallback to CLOCK_REALTIME in that case too. No
real reason to have a different behavior depending only on the installed
mach_host.defs file :)

Thanks!

Samuel

> +           }
> +         else
> +           __set_errno (err);
> +         return -1;
> +       }
> +     TIME_VALUE64_TO_TIMESPEC (&tv, ts);
> +     return 0;
> +      }
> +#endif
> +
>      case CLOCK_REALTIME:
>        {
>       /* __host_get_time can only fail if passed an invalid host_t.
> diff --git a/sysdeps/mach/configure b/sysdeps/mach/configure
> index abfe084fda..8aa6bbb18b 100644
> --- a/sysdeps/mach/configure
> +++ b/sysdeps/mach/configure
> @@ -461,6 +461,36 @@ if test $libc_cv_mach_rpc_host_page_size = yes; then
>  
>  fi
>  
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for host_get_uptime64 
> in mach_host.defs" >&5
> +printf %s "checking for host_get_uptime64 in mach_host.defs... " >&6; }
> +if test ${libc_cv_mach_rpc_host_get_uptime64+y}
> +then :
> +  printf %s "(cached) " >&6
> +else case e in #(
> +  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +#include <mach/mach_host.defs>
> +
> +_ACEOF
> +if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
> +  $EGREP_TRADITIONAL "host_get_uptime64" >/dev/null 2>&1
> +then :
> +  libc_cv_mach_rpc_host_get_uptime64=yes
> +else case e in #(
> +  e) libc_cv_mach_rpc_host_get_uptime64=no ;;
> +esac
> +fi
> +rm -rf conftest*
> + ;;
> +esac
> +fi
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: 
> $libc_cv_mach_rpc_host_get_uptime64" >&5
> +printf "%s\n" "$libc_cv_mach_rpc_host_get_uptime64" >&6; }
> +if test $libc_cv_mach_rpc_host_get_uptime64 = yes; then
> +  printf "%s\n" "#define HAVE_HOST_GET_UPTIME64 1" >>confdefs.h
> +
> +fi
> +
>  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for thread_set_name 
> in gnumach.defs" >&5
>  printf %s "checking for thread_set_name in gnumach.defs... " >&6; }
>  if test ${libc_cv_mach_rpc_thread_set_name+y}
> diff --git a/sysdeps/mach/configure.ac b/sysdeps/mach/configure.ac
> index 6dfa2b3518..08e5fdefe9 100644
> --- a/sysdeps/mach/configure.ac
> +++ b/sysdeps/mach/configure.ac
> @@ -92,6 +92,8 @@ fi
>  
>  mach_RPC_CHECK(mach_host.defs, host_page_size,
>              HAVE_HOST_PAGE_SIZE)
> +mach_RPC_CHECK(mach_host.defs, host_get_uptime64,
> +            HAVE_HOST_GET_UPTIME64)
>  mach_RPC_CHECK(gnumach.defs, thread_set_name,
>              HAVE_MACH_THREAD_SET_NAME)
>  mach_RPC_CHECK(gnumach.defs, thread_get_name,
> -- 
> 2.45.2
> 
> 

-- 
Samuel
+#if defined(__alpha__) && defined(CONFIG_PCI)
+       /*
+        * The meaning of life, the universe, and everything. Plus
+        * this makes the year come out right.
+        */
+       year -= 42;
+#endif
(From the patch for 1.3.2: (kernel/time.c), submitted by Marcus Meissner)