[Qemu-devel] [PATCH] kvm: Improve upgrade notes when facing unsupported kernels

[Jan Kiszka <jan.kiszka@web.de>]

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Users complained that it is not obvious what to do when kvm refuses to
build or run due to an unsupported host kernel, so let's improve the
hints.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

 configure |    6 ++++--
 kvm-all.c |   10 +++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/configure b/configure
index 42d46f2..8ccb58c 100755
--- a/configure
+++ b/configure
@@ -1158,7 +1158,9 @@ EOF
 	| grep "error: " \
 	| awk -F "error: " '{if (NR>1) printf(", "); printf("%s",$2);}'`
       if test "$kvmerr" != "" ; then
-        kvm="no - (${kvmerr})"
+        kvm="no - (${kvmerr})\n\
+    NOTE: To enable KVM support, update your kernel to 2.6.29+ or install \
+recent kvm-kmod from http://sourceforge.net/projects/kvm."
       fi
     fi
   fi
@@ -1377,7 +1379,7 @@ echo "vde support       $vde"
 echo "AIO support       $aio"
 echo "IO thread         $io_thread"
 echo "Install blobs     $blobs"
-echo "KVM support       $kvm"
+echo -e "KVM support       $kvm"
 echo "fdt support       $fdt"
 echo "preadv support    $preadv"
 
diff --git a/kvm-all.c b/kvm-all.c
index dc2ded5..8567ac9 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -396,6 +396,9 @@ int kvm_check_extension(KVMState *s, unsigned int extension)
 
 int kvm_init(int smp_cpus)
 {
+    static const char upgrade_note[] =
+        "Please upgrade to at least kernel 2.6.29 or recent kvm-kmod\n"
+        "(see http://sourceforge.net/projects/kvm).\n";
     KVMState *s;
     int ret;
     int i;
@@ -446,7 +449,8 @@ int kvm_init(int smp_cpus)
      */
     if (!kvm_check_extension(s, KVM_CAP_USER_MEMORY)) {
         ret = -EINVAL;
-        fprintf(stderr, "kvm does not support KVM_CAP_USER_MEMORY\n");
+        fprintf(stderr, "kvm does not support KVM_CAP_USER_MEMORY\n%s",
+                upgrade_note);
         goto err;
     }
 
@@ -457,8 +461,8 @@ int kvm_init(int smp_cpus)
         ret = -EINVAL;
 
         fprintf(stderr,
-                "KVM kernel module broken (DESTROY_MEMORY_REGION)\n"
-                "Please upgrade to at least kvm-81.\n");
+                "KVM kernel module broken (DESTROY_MEMORY_REGION).\n%s",
+                upgrade_note);
         goto err;
     }
 


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