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Introduce qemu_madvise()

Browse source 
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>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Andreas Färber 2010-09-25 11:26:05 +00:00 • committed by Blue Swirl
parent d63cb48db9
commit e78815a554
8 changed files with 100 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

33
configure vendored
View file

@ -2071,6 +2071,31 @@ if compile_prog "" "" ; then
fdatasync=yes
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
@ -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