Re: [Qemu-devel] [PATCH] oslib-posix: check for posix_memalign in configure script

[Kamil Rytarowski]

On 04.01.2018 18:39, Andreas Gustafsson wrote:
> Check for the presence of posix_memalign() in the configure script,
> not using "defined(_POSIX_C_SOURCE) && !defined(__sun__)".  This
> lets qemu use posix_memalign() on NetBSD versions that have it,
> instead of falling back to valloc() which is wasteful when the
> required alignment is smaller than a page.
> 
> Signed-off-by: Andreas Gustafsson <address@hidden>

Reviewed-by: Kamil Rytarowski <address@hidden>

> ---
>  configure          | 19 +++++++++++++++++++
>  util/oslib-posix.c |  2 +-
>  2 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 100309c33f..9f8580332a 100755
> --- a/configure
> +++ b/configure
> @@ -4573,6 +4573,21 @@ if compile_prog "" "" ; then
>      posix_madvise=yes
>  fi
>  
> +##########################################
> +# check if we have posix_memalign()
> +
> +posix_memalign=no
> +cat > $TMPC << EOF
> +#include <stdlib.h>
> +int main(void) {
> +    void *p;
> +    return posix_memalign(&p, 8, 8);
> +}
> +EOF
> +if compile_prog "" "" ; then
> +    posix_memalign=yes
> +fi
> +
>  ##########################################
>  # check if we have posix_syslog
>  
> @@ -5542,6 +5557,7 @@ echo "preadv support    $preadv"
>  echo "fdatasync         $fdatasync"
>  echo "madvise           $madvise"
>  echo "posix_madvise     $posix_madvise"
> +echo "posix_memalign    $posix_memalign"
>  echo "libcap-ng support $cap_ng"
>  echo "vhost-net support $vhost_net"
>  echo "vhost-scsi support $vhost_scsi"
> @@ -6015,6 +6031,9 @@ fi
>  if test "$posix_madvise" = "yes" ; then
>    echo "CONFIG_POSIX_MADVISE=y" >> $config_host_mak
>  fi
> +if test "$posix_memalign" = "yes" ; then
> +  echo "CONFIG_POSIX_MEMALIGN=y" >> $config_host_mak
> +fi
>  
>  if test "$spice" = "yes" ; then
>    echo "CONFIG_SPICE=y" >> $config_host_mak
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index 77369c92ce..4655bc1f89 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -105,7 +105,7 @@ void *qemu_try_memalign(size_t alignment, size_t size)
>          alignment = sizeof(void*);
>      }
>  
> -#if defined(_POSIX_C_SOURCE) && !defined(__sun__)
> +#if defined(CONFIG_POSIX_MEMALIGN)
>      int ret;
>      ret = posix_memalign(&ptr, alignment, size);
>      if (ret != 0) {
>

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