[PATCH 2/3] kvm-userspace: kvmppc: fix hostlonbits detection when cross compiling

[PATCH 2/3] kvm-userspace: kvmppc: fix hostlonbits detection when cross compiling

[ehrhardt]

From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>

A recent kvm merge with qemu brought code for 64bit power that broke cross
compilation. The issue is caused by configure trying to execute target
architecture binaries where configure is executed.

I tried to change that detection so that it works with&without cross
compilation with only a small change and especially without an addtional
configure command line switch. Including the bits/wordsize.h header a platform
usually can check its wordsize and by doing that configure can check the
hostlongbits without executing the binary. Instead it now stops after
preprocessing stage which resolved the __WORDSIZE constant and retrieves
that value.

I don't like my new check style, but it is at least less broken than before.
Another approach that was suggested was that qemu might end up needing
something like asm-offsets in the kernel to manage architecture sizes etc.
Comments and other approaches welcome.
 
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
---

[diffstat]
 configure |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

[diff]

diff --git a/qemu/configure b/qemu/configure
--- a/qemu/configure
+++ b/qemu/configure
@@ -685,14 +685,15 @@
 # ppc specific hostlongbits selection
 if test "$cpu" = "powerpc" ; then
     cat > $TMPC <<EOF
-int main(void){return sizeof(long);}
+#include <bits/wordsize.h>
+__WORDSIZE
 EOF
 
-    if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null; then
-        $TMPE
-        case $? in
-            4) hostlongbits="32";;
-            8) hostlongbits="64";;
+    if $cc $ARCH_CFLAGS -E -o $TMPE.E $TMPC 2> /dev/null; then
+        wordsize=`tail -n 1 ${TMPE}.E`
+        case $wordsize in
+            32) hostlongbits="32";;
+            64) hostlongbits="64";;
             *) echo "Couldn't determine bits per long value"; exit 1;;
         esac
     else

[PATCH 0/3] kvm-userspace: kvmppc: fix build for ppc

[ehrhardt]

From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>

Updating and testing kvm-userspace for ppc after a too long time brought up
some issues fixed in this series.

The patches are small and their description should be comprehendible. Due to
the fact that most of the issues where build time issues I also started to
discuss about/establish some kind of automated build test for us that should
allow us to find such things faster.
let me know if qumranet has such a process for x86 already and I should help
you to include ppc.

[patches in series]
[PATCH 1/3] kvm-userspace: kvmppc: fix file header in libkvm-powerpc.c
[PATCH 2/3] kvm-userspace: kvmppc: fix hostlonbits detection when cross compiling
[PATCH 3/3] kvm-userspace: kvmppc: fix building userspace for powerpc

---
[diffstat]
 Makefile                       |    3 ++-
 kernel/powerpc/Makefile.pre    |    1 +
 kernel/powerpc/hack-module.awk |    5 +++++
 libkvm/libkvm-powerpc.c        |   14 +++++---------
 qemu/Makefile.target           |    2 +-
 qemu/configure                 |   13 +++++++------
 6 files changed, 21 insertions(+), 17 deletions(-)

[PATCH 2/3] kvm-userspace: kvmppc: fix hostlonbits detection when cross compiling

[ehrhardt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8]

From: Christian Ehrhardt <ehrhardt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>

The kvm merge with qemu brought code for 64bit power that broke cross
compilation. The issue is caused by configure trying to execute target
architecture binaries where configure is executed.

I tried to change that detection so that it works with&without cross
compilation with only a small change and especially without an addtional
configure command line switch. Including the bits/wordsize.h header a platform
usually can check its wordsize and by doing that configure can check the
hostlongbits without executing the binary. Instead it now stops after
preprocessing stage which resolved the __WORDSIZE constant and retrieves
that value.

I don't like that check style, but it is at least less broken than before.
Comments and other approaches welcome.

Signed-off-by: Christian Ehrhardt <ehrhardt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
---

[diffstat]
 configure |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

[diff]

diff --git a/qemu/configure b/qemu/configure
--- a/qemu/configure
+++ b/qemu/configure
@@ -685,14 +685,15 @@
 # ppc specific hostlongbits selection
 if test "$cpu" = "powerpc" ; then
     cat > $TMPC <<EOF
-int main(void){return sizeof(long);}
+#include <bits/wordsize.h>
+__WORDSIZE
 EOF
 
-    if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null; then
-        $TMPE
-        case $? in
-            4) hostlongbits="32";;
-            8) hostlongbits="64";;
+    if $cc $ARCH_CFLAGS -E -o $TMPE.E $TMPC 2> /dev/null; then
+        wordsize=`tail -n 1 ${TMPE}.E`
+        case $wordsize in
+            32) hostlongbits="32";;
+            64) hostlongbits="64";;
             *) echo "Couldn't determine bits per long value"; exit 1;;
         esac
     else
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