[PATCH] runqemu: more verbose error message about missing qemuboot.conf

[Patrick Ohly <patrick.ohly@intel.com>]

When invoking "runqemu" with a mistyped image or architecture name,
the resulting error message is about the missing qemuboot.conf,
without any indication about the root cause:

 $ runqemu core-image-mimimal ext4 intel-corei7-64
 runqemu - INFO - Assuming MACHINE = intel-corei7-64
 runqemu - INFO - Running MACHINE=intel-corei7-64 bitbake -e...
 runqemu - INFO - MACHINE: intel-corei7-64
 runqemu - INFO - DEPLOY_DIR_IMAGE: /fast/build/refkit/intel-corei7-64/tmp-glibc/deploy/images/intel-corei7-64
 Traceback (most recent call last):
   File "/work/openembedded-core/scripts/runqemu", line 1095, in <module>
     ret = main()
   File "/work/openembedded-core/scripts/runqemu", line 1082, in main
     config.read_qemuboot()
   File "/work/openembedded-core/scripts/runqemu", line 643, in read_qemuboot
     raise Exception("Failed to find <image>.qemuboot.conf!")
 Exception: Failed to find <image>.qemuboot.conf!

Including the name of the actual file the scripts expects to find plus
adding some hints what to check for might help. The error now is:

 $ runqemu core-image-mimimal ext4 intel-corei7-64
 ...
 Exception: Failed to find <image>.qemuboot.conf = .../tmp-glibc/deploy/images/intel-corei7-64/core-image-mimimal-intel-corei7-64.qemuboot.conf (wrong image name or BSP does not support running under qemu?).

The comment about the BSP is included because that would be the real
reason why the file might be missing.

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
---
 scripts/runqemu | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/runqemu b/scripts/runqemu
index 10947bb3edc..eaf38384a5b 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -640,7 +640,7 @@ class BaseConfig(object):
             return
 
         if not os.path.exists(self.qemuboot):
-            raise Exception("Failed to find <image>.qemuboot.conf!")
+            raise Exception("Failed to find <image>.qemuboot.conf = %s (wrong image name or BSP does not support running under qemu?)." % self.qemuboot)
 
         logger.info('CONFFILE: %s' % self.qemuboot)
 
-- 
2.11.0