Patchwork [v8] Introduce qemu_madvise()

login
register
mail settings
Submitter Andreas Färber
Date Sept. 25, 2010, 10:58 a.m.
Message ID <1285412289-3253-1-git-send-email-andreas.faerber@web.de>
Download mbox | patch
Permalink /patch/65742/
State New
Headers show

Comments

Andreas Färber - Sept. 25, 2010, 10:58 a.m.
From: Andreas Färber <afaerber@opensolaris.org>

vl.c has a Sun-specific hack to supply a prototype for madvise(),
but the call site has apparently moved to arch_init.c.

Haiku doesn't implement madvise() in favor of posix_madvise().
OpenBSD and Solaris 10 don't implement posix_madvise() but madvise().
MinGW implements neither.

Check for madvise() and posix_madvise() in configure and supply qemu_madvise()
as wrapper. Prefer madvise() over posix_madvise() due to flag availability.
Convert all callers to use qemu_madvise() and QEMU_MADV_*.

Note that on Solaris the warning is fixed by moving the madvise() prototype,
not by qemu_madvise() itself. It helps with porting though, and it simplifies
most call sites.

v7 -> v8:
* Some versions of MinGW have no sys/mman.h header. Reported by Blue Swirl.

v6 -> v7:
* Adopt madvise() rather than posix_madvise() semantics for returning errors.
* Use EINVAL in place of ENOTSUP.

v5 -> v6:
* Replace two leftover instances of POSIX_MADV_NORMAL with QEMU_MADV_INVALID.
  Spotted by Blue Swirl.

v4 -> v5:
* Introduce QEMU_MADV_INVALID, suggested by Alexander Graf.
  Note that this relies on -1 not being a valid advice value.

v3 -> v4:
* Eliminate #ifdefs at qemu_advise() call sites. Requested by Blue Swirl.
  This will currently break the check in kvm-all.c by calling madvise() with
  a supported flag, which will not fail. Ideas/patches welcome.

v2 -> v3:
* Reuse the *_MADV_* defines for QEMU_MADV_*. Suggested by Alexander Graf.
* Add configure check for madvise(), too.
  Add defines to Makefile, not QEMU_CFLAGS.
  Convert all callers, untested. Suggested by Blue Swirl.
* Keep Solaris' madvise() prototype around. Pointed out by Alexander Graf.
* Display configure check results.

v1 -> v2:
* Don't rely on posix_madvise() availability, add qemu_madvise().
  Suggested by Blue Swirl.

Signed-off-by: Andreas Färber <afaerber@opensolaris.org>
Cc: Blue Swirl <blauwirbel@gmail.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
---
 arch_init.c         |    2 +-
 configure           |   33 +++++++++++++++++++++++++++++++++
 exec.c              |    8 ++------
 hw/virtio-balloon.c |    4 ++--
 kvm-all.c           |   12 ++++--------
 osdep.c             |   22 ++++++++++++++++++++++
 osdep.h             |   35 +++++++++++++++++++++++++++++++++++
 vl.c                |    3 ---
 8 files changed, 99 insertions(+), 20 deletions(-)
Blue Swirl - Sept. 25, 2010, 3:17 p.m.
Thanks, applied. I moved the include line below #include
"config-host.h", otherwise CONFIG_xx would have been undefined.

On Sat, Sep 25, 2010 at 10:58 AM, Andreas Färber <andreas.faerber@web.de> wrote:
> From: Andreas Färber <afaerber@opensolaris.org>
>
> vl.c has a Sun-specific hack to supply a prototype for madvise(),
> but the call site has apparently moved to arch_init.c.
>
> Haiku doesn't implement madvise() in favor of posix_madvise().
> OpenBSD and Solaris 10 don't implement posix_madvise() but madvise().
> MinGW implements neither.
>
> Check for madvise() and posix_madvise() in configure and supply qemu_madvise()
> as wrapper. Prefer madvise() over posix_madvise() due to flag availability.
> Convert all callers to use qemu_madvise() and QEMU_MADV_*.
>
> Note that on Solaris the warning is fixed by moving the madvise() prototype,
> not by qemu_madvise() itself. It helps with porting though, and it simplifies
> most call sites.
>
> v7 -> v8:
> * Some versions of MinGW have no sys/mman.h header. Reported by Blue Swirl.
>
> v6 -> v7:
> * Adopt madvise() rather than posix_madvise() semantics for returning errors.
> * Use EINVAL in place of ENOTSUP.
>
> v5 -> v6:
> * Replace two leftover instances of POSIX_MADV_NORMAL with QEMU_MADV_INVALID.
>  Spotted by Blue Swirl.
>
> v4 -> v5:
> * Introduce QEMU_MADV_INVALID, suggested by Alexander Graf.
>  Note that this relies on -1 not being a valid advice value.
>
> v3 -> v4:
> * Eliminate #ifdefs at qemu_advise() call sites. Requested by Blue Swirl.
>  This will currently break the check in kvm-all.c by calling madvise() with
>  a supported flag, which will not fail. Ideas/patches welcome.
>
> v2 -> v3:
> * Reuse the *_MADV_* defines for QEMU_MADV_*. Suggested by Alexander Graf.
> * Add configure check for madvise(), too.
>  Add defines to Makefile, not QEMU_CFLAGS.
>  Convert all callers, untested. Suggested by Blue Swirl.
> * Keep Solaris' madvise() prototype around. Pointed out by Alexander Graf.
> * Display configure check results.
>
> v1 -> v2:
> * Don't rely on posix_madvise() availability, add qemu_madvise().
>  Suggested by Blue Swirl.
>
> Signed-off-by: Andreas Färber <afaerber@opensolaris.org>
> Cc: Blue Swirl <blauwirbel@gmail.com>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> ---
>  arch_init.c         |    2 +-
>  configure           |   33 +++++++++++++++++++++++++++++++++
>  exec.c              |    8 ++------
>  hw/virtio-balloon.c |    4 ++--
>  kvm-all.c           |   12 ++++--------
>  osdep.c             |   22 ++++++++++++++++++++++
>  osdep.h             |   35 +++++++++++++++++++++++++++++++++++
>  vl.c                |    3 ---
>  8 files changed, 99 insertions(+), 20 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index e468c0c..a910033 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -396,7 +396,7 @@ int ram_load(QEMUFile *f, void *opaque, int version_id)
>  #ifndef _WIN32
>             if (ch == 0 &&
>                 (!kvm_enabled() || kvm_has_sync_mmu())) {
> -                madvise(host, TARGET_PAGE_SIZE, MADV_DONTNEED);
> +                qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
>             }
>  #endif
>         } else if (flags & RAM_SAVE_FLAG_PAGE) {
> diff --git a/configure b/configure
> index 3bfc5e9..6a21bf2 100755
> --- a/configure
> +++ b/configure
> @@ -2072,6 +2072,31 @@ if compile_prog "" "" ; then
>  fi
>
>  ##########################################
> +# check if we have madvise
> +
> +madvise=no
> +cat > $TMPC << EOF
> +#include <sys/types.h>
> +#include <sys/mman.h>
> +int main(void) { return madvise(NULL, 0, MADV_DONTNEED); }
> +EOF
> +if compile_prog "" "" ; then
> +    madvise=yes
> +fi
> +
> +##########################################
> +# check if we have posix_madvise
> +
> +posix_madvise=no
> +cat > $TMPC << EOF
> +#include <sys/mman.h>
> +int main(void) { return posix_madvise(NULL, 0, POSIX_MADV_DONTNEED); }
> +EOF
> +if compile_prog "" "" ; then
> +    posix_madvise=yes
> +fi
> +
> +##########################################
>  # check if trace backend exists
>
>  sh "$source_path/tracetool" "--$trace_backend" --check-backend > /dev/null 2> /dev/null
> @@ -2238,6 +2263,8 @@ echo "KVM support       $kvm"
>  echo "fdt support       $fdt"
>  echo "preadv support    $preadv"
>  echo "fdatasync         $fdatasync"
> +echo "madvise           $madvise"
> +echo "posix_madvise     $posix_madvise"
>  echo "uuid support      $uuid"
>  echo "vhost-net support $vhost_net"
>  echo "Trace backend     $trace_backend"
> @@ -2478,6 +2505,12 @@ fi
>  if test "$fdatasync" = "yes" ; then
>   echo "CONFIG_FDATASYNC=y" >> $config_host_mak
>  fi
> +if test "$madvise" = "yes" ; then
> +  echo "CONFIG_MADVISE=y" >> $config_host_mak
> +fi
> +if test "$posix_madvise" = "yes" ; then
> +  echo "CONFIG_POSIX_MADVISE=y" >> $config_host_mak
> +fi
>
>  # XXX: suppress that
>  if [ "$bsd" = "yes" ] ; then
> diff --git a/exec.c b/exec.c
> index 380dab5..9b5464f 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2841,9 +2841,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
>             new_block->host = file_ram_alloc(new_block, size, mem_path);
>             if (!new_block->host) {
>                 new_block->host = qemu_vmalloc(size);
> -#ifdef MADV_MERGEABLE
> -                madvise(new_block->host, size, MADV_MERGEABLE);
> -#endif
> +                qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
>             }
>  #else
>             fprintf(stderr, "-mem-path option unsupported\n");
> @@ -2858,9 +2856,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
>  #else
>             new_block->host = qemu_vmalloc(size);
>  #endif
> -#ifdef MADV_MERGEABLE
> -            madvise(new_block->host, size, MADV_MERGEABLE);
> -#endif
> +            qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
>         }
>     }
>
> diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
> index 9fe3886..1e74674 100644
> --- a/hw/virtio-balloon.c
> +++ b/hw/virtio-balloon.c
> @@ -51,8 +51,8 @@ static void balloon_page(void *addr, int deflate)
>  {
>  #if defined(__linux__)
>     if (!kvm_enabled() || kvm_has_sync_mmu())
> -        madvise(addr, TARGET_PAGE_SIZE,
> -                deflate ? MADV_WILLNEED : MADV_DONTNEED);
> +        qemu_madvise(addr, TARGET_PAGE_SIZE,
> +                deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
>  #endif
>  }
>
> diff --git a/kvm-all.c b/kvm-all.c
> index 58b0404..1cc696f 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1031,18 +1031,14 @@ int kvm_has_xcrs(void)
>  void kvm_setup_guest_memory(void *start, size_t size)
>  {
>     if (!kvm_has_sync_mmu()) {
> -#ifdef MADV_DONTFORK
> -        int ret = madvise(start, size, MADV_DONTFORK);
> +        int ret = qemu_madvise(start, size, QEMU_MADV_DONTFORK);
>
>         if (ret) {
> -            perror("madvice");
> +            perror("qemu_madvise");
> +            fprintf(stderr,
> +                    "Need MADV_DONTFORK in absence of synchronous KVM MMU\n");
>             exit(1);
>         }
> -#else
> -        fprintf(stderr,
> -                "Need MADV_DONTFORK in absence of synchronous KVM MMU\n");
> -        exit(1);
> -#endif
>     }
>  }
>
> diff --git a/osdep.c b/osdep.c
> index 30426ff..2c53015 100644
> --- a/osdep.c
> +++ b/osdep.c
> @@ -28,6 +28,9 @@
>  #include <errno.h>
>  #include <unistd.h>
>  #include <fcntl.h>
> +#if defined(CONFIG_MADVISE) || defined(CONFIG_POSIX_MADVISE)
> +#include <sys/mman.h>
> +#endif
>
>  /* Needed early for CONFIG_BSD etc. */
>  #include "config-host.h"
> @@ -35,6 +38,9 @@
>  #ifdef CONFIG_SOLARIS
>  #include <sys/types.h>
>  #include <sys/statvfs.h>
> +/* See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for
> +   discussion about Solaris header problems */
> +extern int madvise(caddr_t, size_t, int);
>  #endif
>
>  #ifdef CONFIG_EVENTFD
> @@ -139,6 +145,22 @@ void qemu_vfree(void *ptr)
>
>  #endif
>
> +int qemu_madvise(void *addr, size_t len, int advice)
> +{
> +    if (advice == QEMU_MADV_INVALID) {
> +        errno = EINVAL;
> +        return -1;
> +    }
> +#if defined(CONFIG_MADVISE)
> +    return madvise(addr, len, advice);
> +#elif defined(CONFIG_POSIX_MADVISE)
> +    return posix_madvise(addr, len, advice);
> +#else
> +    errno = EINVAL;
> +    return -1;
> +#endif
> +}
> +
>  int qemu_create_pidfile(const char *filename)
>  {
>     char buffer[128];
> diff --git a/osdep.h b/osdep.h
> index 1cdc7e2..6716281 100644
> --- a/osdep.h
> +++ b/osdep.h
> @@ -90,6 +90,41 @@ void *qemu_memalign(size_t alignment, size_t size);
>  void *qemu_vmalloc(size_t size);
>  void qemu_vfree(void *ptr);
>
> +#define QEMU_MADV_INVALID -1
> +
> +#if defined(CONFIG_MADVISE)
> +
> +#define QEMU_MADV_WILLNEED  MADV_WILLNEED
> +#define QEMU_MADV_DONTNEED  MADV_DONTNEED
> +#ifdef MADV_DONTFORK
> +#define QEMU_MADV_DONTFORK  MADV_DONTFORK
> +#else
> +#define QEMU_MADV_DONTFORK  QEMU_MADV_INVALID
> +#endif
> +#ifdef MADV_MERGEABLE
> +#define QEMU_MADV_MERGEABLE MADV_MERGEABLE
> +#else
> +#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
> +#endif
> +
> +#elif defined(CONFIG_POSIX_MADVISE)
> +
> +#define QEMU_MADV_WILLNEED  POSIX_MADV_WILLNEED
> +#define QEMU_MADV_DONTNEED  POSIX_MADV_DONTNEED
> +#define QEMU_MADV_DONTFORK  QEMU_MADV_INVALID
> +#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
> +
> +#else /* no-op */
> +
> +#define QEMU_MADV_WILLNEED  QEMU_MADV_INVALID
> +#define QEMU_MADV_DONTNEED  QEMU_MADV_INVALID
> +#define QEMU_MADV_DONTFORK  QEMU_MADV_INVALID
> +#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
> +
> +#endif
> +
> +int qemu_madvise(void *addr, size_t len, int advice);
> +
>  int qemu_create_pidfile(const char *filename);
>
>  #ifdef _WIN32
> diff --git a/vl.c b/vl.c
> index 3f45aa9..d352d18 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -80,9 +80,6 @@
>  #include <net/if.h>
>  #include <syslog.h>
>  #include <stropts.h>
> -/* See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for
> -   discussion about Solaris header problems */
> -extern int madvise(caddr_t, size_t, int);
>  #endif
>  #endif
>  #endif
> --
> 1.7.2.2
>
>

Patch

diff --git a/arch_init.c b/arch_init.c
index e468c0c..a910033 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -396,7 +396,7 @@  int ram_load(QEMUFile *f, void *opaque, int version_id)
 #ifndef _WIN32
             if (ch == 0 &&
                 (!kvm_enabled() || kvm_has_sync_mmu())) {
-                madvise(host, TARGET_PAGE_SIZE, MADV_DONTNEED);
+                qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
             }
 #endif
         } else if (flags & RAM_SAVE_FLAG_PAGE) {
diff --git a/configure b/configure
index 3bfc5e9..6a21bf2 100755
--- a/configure
+++ b/configure
@@ -2072,6 +2072,31 @@  if compile_prog "" "" ; then
 fi
 
 ##########################################
+# check if we have madvise
+
+madvise=no
+cat > $TMPC << EOF
+#include <sys/types.h>
+#include <sys/mman.h>
+int main(void) { return madvise(NULL, 0, MADV_DONTNEED); }
+EOF
+if compile_prog "" "" ; then
+    madvise=yes
+fi
+
+##########################################
+# check if we have posix_madvise
+
+posix_madvise=no
+cat > $TMPC << EOF
+#include <sys/mman.h>
+int main(void) { return posix_madvise(NULL, 0, POSIX_MADV_DONTNEED); }
+EOF
+if compile_prog "" "" ; then
+    posix_madvise=yes
+fi
+
+##########################################
 # check if trace backend exists
 
 sh "$source_path/tracetool" "--$trace_backend" --check-backend > /dev/null 2> /dev/null
@@ -2238,6 +2263,8 @@  echo "KVM support       $kvm"
 echo "fdt support       $fdt"
 echo "preadv support    $preadv"
 echo "fdatasync         $fdatasync"
+echo "madvise           $madvise"
+echo "posix_madvise     $posix_madvise"
 echo "uuid support      $uuid"
 echo "vhost-net support $vhost_net"
 echo "Trace backend     $trace_backend"
@@ -2478,6 +2505,12 @@  fi
 if test "$fdatasync" = "yes" ; then
   echo "CONFIG_FDATASYNC=y" >> $config_host_mak
 fi
+if test "$madvise" = "yes" ; then
+  echo "CONFIG_MADVISE=y" >> $config_host_mak
+fi
+if test "$posix_madvise" = "yes" ; then
+  echo "CONFIG_POSIX_MADVISE=y" >> $config_host_mak
+fi
 
 # XXX: suppress that
 if [ "$bsd" = "yes" ] ; then
diff --git a/exec.c b/exec.c
index 380dab5..9b5464f 100644
--- a/exec.c
+++ b/exec.c
@@ -2841,9 +2841,7 @@  ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
             new_block->host = file_ram_alloc(new_block, size, mem_path);
             if (!new_block->host) {
                 new_block->host = qemu_vmalloc(size);
-#ifdef MADV_MERGEABLE
-                madvise(new_block->host, size, MADV_MERGEABLE);
-#endif
+                qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
             }
 #else
             fprintf(stderr, "-mem-path option unsupported\n");
@@ -2858,9 +2856,7 @@  ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
 #else
             new_block->host = qemu_vmalloc(size);
 #endif
-#ifdef MADV_MERGEABLE
-            madvise(new_block->host, size, MADV_MERGEABLE);
-#endif
+            qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
         }
     }
 
diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
index 9fe3886..1e74674 100644
--- a/hw/virtio-balloon.c
+++ b/hw/virtio-balloon.c
@@ -51,8 +51,8 @@  static void balloon_page(void *addr, int deflate)
 {
 #if defined(__linux__)
     if (!kvm_enabled() || kvm_has_sync_mmu())
-        madvise(addr, TARGET_PAGE_SIZE,
-                deflate ? MADV_WILLNEED : MADV_DONTNEED);
+        qemu_madvise(addr, TARGET_PAGE_SIZE,
+                deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
 #endif
 }
 
diff --git a/kvm-all.c b/kvm-all.c
index 58b0404..1cc696f 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1031,18 +1031,14 @@  int kvm_has_xcrs(void)
 void kvm_setup_guest_memory(void *start, size_t size)
 {
     if (!kvm_has_sync_mmu()) {
-#ifdef MADV_DONTFORK
-        int ret = madvise(start, size, MADV_DONTFORK);
+        int ret = qemu_madvise(start, size, QEMU_MADV_DONTFORK);
 
         if (ret) {
-            perror("madvice");
+            perror("qemu_madvise");
+            fprintf(stderr,
+                    "Need MADV_DONTFORK in absence of synchronous KVM MMU\n");
             exit(1);
         }
-#else
-        fprintf(stderr,
-                "Need MADV_DONTFORK in absence of synchronous KVM MMU\n");
-        exit(1);
-#endif
     }
 }
 
diff --git a/osdep.c b/osdep.c
index 30426ff..2c53015 100644
--- a/osdep.c
+++ b/osdep.c
@@ -28,6 +28,9 @@ 
 #include <errno.h>
 #include <unistd.h>
 #include <fcntl.h>
+#if defined(CONFIG_MADVISE) || defined(CONFIG_POSIX_MADVISE)
+#include <sys/mman.h>
+#endif
 
 /* Needed early for CONFIG_BSD etc. */
 #include "config-host.h"
@@ -35,6 +38,9 @@ 
 #ifdef CONFIG_SOLARIS
 #include <sys/types.h>
 #include <sys/statvfs.h>
+/* See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for
+   discussion about Solaris header problems */
+extern int madvise(caddr_t, size_t, int);
 #endif
 
 #ifdef CONFIG_EVENTFD
@@ -139,6 +145,22 @@  void qemu_vfree(void *ptr)
 
 #endif
 
+int qemu_madvise(void *addr, size_t len, int advice)
+{
+    if (advice == QEMU_MADV_INVALID) {
+        errno = EINVAL;
+        return -1;
+    }
+#if defined(CONFIG_MADVISE)
+    return madvise(addr, len, advice);
+#elif defined(CONFIG_POSIX_MADVISE)
+    return posix_madvise(addr, len, advice);
+#else
+    errno = EINVAL;
+    return -1;
+#endif
+}
+
 int qemu_create_pidfile(const char *filename)
 {
     char buffer[128];
diff --git a/osdep.h b/osdep.h
index 1cdc7e2..6716281 100644
--- a/osdep.h
+++ b/osdep.h
@@ -90,6 +90,41 @@  void *qemu_memalign(size_t alignment, size_t size);
 void *qemu_vmalloc(size_t size);
 void qemu_vfree(void *ptr);
 
+#define QEMU_MADV_INVALID -1
+
+#if defined(CONFIG_MADVISE)
+
+#define QEMU_MADV_WILLNEED  MADV_WILLNEED
+#define QEMU_MADV_DONTNEED  MADV_DONTNEED
+#ifdef MADV_DONTFORK
+#define QEMU_MADV_DONTFORK  MADV_DONTFORK
+#else
+#define QEMU_MADV_DONTFORK  QEMU_MADV_INVALID
+#endif
+#ifdef MADV_MERGEABLE
+#define QEMU_MADV_MERGEABLE MADV_MERGEABLE
+#else
+#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
+#endif
+
+#elif defined(CONFIG_POSIX_MADVISE)
+
+#define QEMU_MADV_WILLNEED  POSIX_MADV_WILLNEED
+#define QEMU_MADV_DONTNEED  POSIX_MADV_DONTNEED
+#define QEMU_MADV_DONTFORK  QEMU_MADV_INVALID
+#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
+
+#else /* no-op */
+
+#define QEMU_MADV_WILLNEED  QEMU_MADV_INVALID
+#define QEMU_MADV_DONTNEED  QEMU_MADV_INVALID
+#define QEMU_MADV_DONTFORK  QEMU_MADV_INVALID
+#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
+
+#endif
+
+int qemu_madvise(void *addr, size_t len, int advice);
+
 int qemu_create_pidfile(const char *filename);
 
 #ifdef _WIN32
diff --git a/vl.c b/vl.c
index 3f45aa9..d352d18 100644
--- a/vl.c
+++ b/vl.c
@@ -80,9 +80,6 @@ 
 #include <net/if.h>
 #include <syslog.h>
 #include <stropts.h>
-/* See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for
-   discussion about Solaris header problems */
-extern int madvise(caddr_t, size_t, int);
 #endif
 #endif
 #endif