Hi everyone,
while running a test when updating kvm-userspace for powerpc I found
that the current kvm userspace requires kvm kernel headers in the
default search path of the used compilers.
I used to update and build in the same kvm-userspace directory for a
while and this one had an old stale kernel/include directory which
fulfilled all the requirements.
While testing my current patch series on a new git clone of
kvm-userspace I wondered why this doesn't work anymore (it worked in my
old directory which also had the updated current source).
I switched to x86 to verify that issue there and I found that eventually
the issue is in the kvm detection "KVM Probe" part of the qemu
configuration in kvm-userspace. It failed not finding kvm headers.
gcc -m32 -o /tmp/qemu-conf--21885-
-I/home/paelzer/Desktop/kvm-userspace/kernel/include
/tmp/qemu-conf--21885-.c
/tmp/qemu-conf--21885-.c:1:23: error: linux/kvm.h: No such file or
directory
/tmp/qemu-conf--21885-.c:3:2: error: #error Invalid KVM version
Looking at the include paths it is worth to note that a current git
clone of kvm-userspace has no kernel/include directory anymore. A few
questions later to some other kvm developers I found that there headers
can be found, but in the default search path of the compiler e.g.
/usr/include. In my environment with an older gcc cross compiler for
powerpc and no up to date linux headers installed for x86 both
architectures failed.
The Solution to that can be done in several ways:
a) we decide that kvm-userspace needs up-to-date kernel headers
installed. And modify the KVM Probe at least to tell the user about this
possible reason when failing instead of silently switching to "KVM
support no".
b) if the user already provide a --kerneldir option to specify where the
right includes can be found we should give those configure checks a
chance to really reach that. Atm it adds the kernel/include path of the
kvm-userspace tree which doesn't exist anymore (except as stale old dir
in a lot of source trees out there).
c) I overlooked something and there is an even better or trivial
approach :-)
Since this could be solved several very different ways I think its worth
a discussion.
As I prefer b) I attached a simple patch example how this could look
like :-).
--
Grüsse / regards,
Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization
diff --git a/configure b/configure
index 63f956c..f772bae 100755
--- a/configure
+++ b/configure
@@ -3,6 +3,7 @@
prefix=/usr/local
kernelsourcedir=
kerneldir=/lib/modules/$(uname -r)/build
+qemu_kerneldir=
cc=gcc
ld=ld
objcopy=objcopy
@@ -56,6 +57,7 @@ while [[ "$1" = -* ]]; do
;;
--kerneldir)
kerneldir="$arg"
+ qemu_kerneldir="$arg"
;;
--with-patched-kernel)
want_module=
@@ -84,9 +86,12 @@ while [[ "$1" = -* ]]; do
esac
done
-
-#set kenel directory
+#set libkvm kernel directory
libkvm_kerneldir=$(readlink -f kernel)
+# use libkvm_kerneldir for qemu if no kerneldir option was set
+if test "$qemu_kerneldir" = "" ; then
+ qemu_kerneldir=$libkvm_kerneldir
+fi
case $arch in
i?86*|x86_64*)
@@ -123,7 +128,7 @@ fi
--disable-gcc-check \
--extra-cflags="-I $PWD/../libkvm $qemu_cflags" \
--extra-ldflags="-L $PWD/../libkvm $qemu_ldflags" \
- --kerneldir="$libkvm_kerneldir" \
+ --kerneldir="$qemu_kerneldir" \
--prefix="$prefix" \
${cross_prefix:+"--cross-prefix=$cross_prefix"} \
${cross_prefix:+"--cpu=$arch"} "${qemu_opts[@]}"
