This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Re: [Pkg-xen-devel] xen 4.1 blktap2 support

On Fri, 2011-04-29 at 12:08 +0100, Bastian Blank wrote:
> On Thu, Apr 28, 2011 at 03:20:58PM +0100, Ian Campbell wrote:
> > On Thu, 2011-04-28 at 14:27 +0200, Bastian Blank wrote:
> > > - Silent fail if qemu-dm[1] is missing or failing. It lacks error
> > >   checking.
> > Yes, this could certainly be improved.
> A hang without any feedback is the worst user-experience possible.

On my systems I get, after ~10s:
libxl: error: libxl_device.c:475:libxl__wait_for_device_model Device Model not 
xl: fatal error: libxl_create.c:515, rc=-1: libxl__confirm_device_model_startup
libxl: debug: libxl_dm.c:890:libxl__destroy_device_model Device Model already 

The following makes the obvious qemu-dm not present / not executable
case fail immediately by adding an access(..., X_OK) check, which is
something of an improvement.

This still leaves the delay for other cases, e.g. immediate failure due
to a missing library, bad parameters etc. I think with a little bit of
refactoring libxl__wait_for_device_model() could incorporate the
necessary check for child exit without simply waiting for the entire
delay. I'll take a closer look at this and the other issues you reported


libxl: check that device model binary is executable.

This causes us to fail more quickly in more obvious failure case of not
having the right binary installed.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

--- a/tools/libxl/libxl_dm.c    Tue May 03 16:53:22 2011 +0100
+++ b/tools/libxl/libxl_dm.c    Tue May 03 17:34:19 2011 +0100
@@ -762,7 +762,12 @@ int libxl__create_device_model(libxl__gc
         rc = ERROR_FAIL;
         goto out;
+    if (access(dm, X_OK) < 0) {
+                         "device model %s is not executable", dm);
+        rc = ERROR_FAIL;
+        goto out;
+    }
     args = libxl__build_device_model_args(gc, dm, info, disks, num_disks,
                                           vifs, num_vifs);
     if (!args) {

Ian Campbell
Current Noise: Karma To Burn - Mt. Penetrator

Winning isn't everything, but losing isn't anything.

Xen-devel mailing list