March 2007 - Devel - libvirt List Archives

[Libvir] A couple of questions about the Python bindings
by Richard W.M. Jones 28 Mar '07

28 Mar '07

virDomainGetUUIDString, virDomainPinVcpu, virNetworkGetUUIDString: These functions don't seem to check whether the parameters are correct. For example, virDomainGetUUIDString doesn't check if the buffer parameter passed from Python is large enough to take the UUID string. virDomainPinVcpu is just plain strange (but I guess that strangeness eminates from the Xen implementation), but it seems possible for the Python code to be wrong about the length of the Vcpu map (string). Shouldn't the length be taken from the string itself? virDomainUndefine, virNetworkUndefine: It's unclear from the libvirt documentation, but it sounds as if these functions invalidate (free) the virDomainPtr / virNetworkPtr object passed to them. (In fact, the Xen implementation of virDomainPtr at least _doesn't_ free it - is that a bug?) If this is the case, then the Python bindings ought to set self._o = None. Rich. -- Emerging Technologies, Red Hat http://et.redhat.com/~rjones/ 64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421 "[Negative numbers] darken the very whole doctrines of the equations and make dark of the things which are in their nature excessively obvious and simple" (Francis Maseres FRS, mathematician, 1759)

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[Libvir] [PATCH] Fix value of XEN_V2_OP_SETMAXMEM
by Masayuki Sunou 28 Mar '07

28 Mar '07

Hi Because the value of XEN_V2_OP_SETMAXMEM in xen_internal.c is wrong, virsh setmaxmem outputs error message. --> Both XEN_V2_OP_SETMAXMEM and XEN_V2_OP_GETVCPUINFO are set to 14, but XEN_V2_OP_SETMAXMEM should be set to 11. -------------------------------------------------------------------------------- # virsh setmaxmem 0 921600 libvir: Xen error : failed Xen syscall ioctl 8518692 -------------------------------------------------------------------------------- This patch sets the right value to XEN_V2_OP_SETMAXMEM. Signed-off-by: Masayuki Sunou <fj1826dm(a)aa.jp.fujitsu.com> Thanks, Masayuki Sunou. -------------------------------------------------------------------------------- Index: libvirt/src/xen_internal.c =================================================================== RCS file: /data/cvs/libvirt/src/xen_internal.c,v retrieving revision 1.67 diff -u -p -r1.67 xen_internal.c --- libvirt/src/xen_internal.c 23 Mar 2007 09:18:24 -0000 1.67 +++ libvirt/src/xen_internal.c 26 Mar 2007 00:09:35 -0000 @@ -280,7 +280,7 @@ typedef struct xen_v0_domainop xen_v0_do */ #define XEN_V0_OP_SETMAXMEM 28 #define XEN_V1_OP_SETMAXMEM 28 -#define XEN_V2_OP_SETMAXMEM 14 +#define XEN_V2_OP_SETMAXMEM 11 struct xen_v0_setmaxmem { domid_t domain; --------------------------------------------------------------------------------

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[Libvir] [PATCH] Fix warn_unused_result when compiling with latest glibc
by Richard W.M. Jones 27 Mar '07

27 Mar '07

I'm not sure if this is the right way to solve this, but it is a way. Rich.

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[Libvir] libvirt not compatible with Xen-unstable hypercall API ?
by Jerone Young 27 Mar '07

27 Mar '07

While trying to verify any potential problem between with libvirt & Xen PPC port. I've found that libvirt currently in CVS attempts to determine what hypercall version to follow, by looking at the hypervisior version. It determines that this is some arbitrary versioning "v2" of the hypercall api. This starts on line 1250 of xen_internal.c. This does not appear to be compatible with current Xen-Unstable from testing and trying to hack it up. Has any work been done toward making libvirt compatible with Xen-unstable that has not been included? Or is it waiting till the offical 3.0.5 release? We are attempting to ensure that Xen PPC works with libvirt. Though we have to use the latest hypercall api. Thanks, Jerone

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[Libvir] [PATCH] pae/nonpae capabilities for paravirt xen guests
by David Lutterkort 26 Mar '07

26 Mar '07

I noticed that the guest capabilities on a xen dom0 always contain both the pae and nonpae feature - AFAIK, you can't mix pae/nonpae guests and hosts, and only one of the features should be there. The attached patch contains the obvious fix. David

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[Libvir] don't clobber user-specified CFLAGS
by Jim Meyering 26 Mar '07

26 Mar '07

Building libvirt with CFLAGS=-g doesn't work as expected: gcc runs without -g. That was due to the following assignment that gives CFLAGS the value of an undefined variable. 2007-03-23 Jim Meyering <jim(a)meyering.net> * acinclude.m4: Remove bogus CFLAGS=$undefined_var assignment that would clobber any CFLAGS setting from e.g., ./autogen.sh CFLAGS=-g. Reported by David Lutterkort. Index: acinclude.m4 =================================================================== RCS file: /data/cvs/libvirt/acinclude.m4,v retrieving revision 1.3 diff -u -p -r1.3 acinclude.m4 --- acinclude.m4 21 Mar 2007 15:22:31 -0000 1.3 +++ acinclude.m4 23 Mar 2007 18:52:55 -0000 @@ -59,8 +59,6 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[ unset option unset try_compiler_flags - CFLAGS="$realsave_CFLAGS" - AC_ARG_ENABLE(iso-c, AC_HELP_STRING([--enable-iso-c], [Try to warn if code is not ISO C ]),,

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[Libvir] [PATCH] Add the message when a little memory is set with setmaxmem.
by Masayuki Sunou 26 Mar '07

26 Mar '07

Hi The message which a cause of an error is hard to detect is displayed when "virsh setmaxmem" sets the maximum memory of an active domain less than Used Memory. -------------------------------------------------------------------------------- # virsh setmaxmem 0 4096 libvir: Xen error : failed Xen syscall ioctl 8518692 libvir: Xen Daemon error : POST operation failed: (xend.err "(22, 'Invalid argument')") libvir: error : library call virDomainSetMaxMemory failed, possibly not supported -------------------------------------------------------------------------------- This patch displays the message which is easier to detect the cause of an error to a user. -------------------------------------------------------------------------------- # virsh setmaxmem 0 4096 error: 4096 is less than current used memory. -------------------------------------------------------------------------------- Signed-off-by: Masayuki Sunou <fj1826dm(a)aa.jp.fujitsu.com> Thanks, Masayuki Sunou. -------------------------------------------------------------------------------- Index: libvirt/src/virsh.c =================================================================== RCS file: /data/cvs/libvirt/src/virsh.c,v retrieving revision 1.67 diff -u -p -r1.67 virsh.c --- libvirt/src/virsh.c 20 Mar 2007 15:31:46 -0000 1.67 +++ libvirt/src/virsh.c 22 Mar 2007 02:27:16 -0000 @@ -1493,6 +1493,7 @@ static int cmdSetmaxmem(vshControl * ctl, vshCmd * cmd) { virDomainPtr dom; + virDomainInfo info; int bytes; int ret = TRUE; @@ -1509,6 +1510,18 @@ cmdSetmaxmem(vshControl * ctl, vshCmd * return FALSE; } + if (virDomainGetID(dom) != ((unsigned int)-1)) { + if (virDomainGetInfo(dom, &info) != 0) { + virDomainFree(dom); + return FALSE; + } + if (bytes < info.memory) { + vshError(ctl, FALSE, _("%d is less than current used memory."), bytes); + virDomainFree(dom); + return FALSE; + } + } + if (virDomainSetMaxMemory(dom, bytes) != 0) { ret = FALSE; } --------------------------------------------------------------------------------

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[Libvir] sprintf cleanup patch
by Daniel Veillard 23 Mar '07

23 Mar '07

Sprintf is potentially dangerous, so I replaced all instances with snprintf (even in cases where the usage was garanteed to be safe to have a coherent approach). Pending patch appended, Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/

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[Libvir] Python bindings, errors & exceptions
by Richard W.M. Jones 23 Mar '07

23 Mar '07

I'm really confused about how the Python bindings are supposed to handle errors. Can someone explain how this is supposed to work? Case in point: currently virt-manager fails because conn.listNetworks () returns None, whereas virt-manager is expecting it to return a list of network objects. The code returns None because the underlying calls (either virConnectNumOfNetworks or virConnectListNetworks) is failing. The functions in question are: class virConnect: # libvirtclass.py # ... def listNetworks(self): """list the networks, stores the pointers to the names in @names """ ret = libvirtmod.virConnectListNetworks(self._o) return ret (the above code is automatically generated by generator.py), and: static PyObject * // libvir.c libvirt_virConnectListNetworks(PyObject *self ATTRIBUTE_UNUSED, PyObject *args) { PyObject *py_retval; char **names = NULL; int c_retval, i; virConnectPtr conn; PyObject *pyobj_conn; // ... c_retval = virConnectNumOfNetworks(conn); if (c_retval < 0) { Py_INCREF(Py_None); return (Py_None); } // ... py_retval = PyList_New(c_retval); if (names) { for (i = 0;i < c_retval;i++) { PyList_SetItem(py_retval, i, libvirt_constcharPtrWrap(names[i])); free(names[i]); } free(names); } return(py_retval); } (I've omitted some code to make the general idea clearer). The upshot is that if the underlying functions fail, at no point is an exception thrown. This is not always the case. For other functions which return C structure pointers (eg. libvirt.open which wraps virConnectOpen), the bindings automatically catch the invalid return and throw an exception. For example: def open(name): # libvirtclass.py """This function should be called first to get a connection to the Hypervisor and xen store """ ret = libvirtmod.virConnectOpen(name) if ret is None:raise libvirtError('virConnectOpen() failed') return virConnect(_obj=ret) It is my view that all errors in C code should turn into Python exceptions. One way to do that would be to have a Python virterror handler which just directly throws the exception. I don't know if this is safe because the exception would unwind through C code, and in some languages that is safe, in others it is not. Another way would be to have a Python virterror handler which remembers that an exception happened, and after each auto-generated function call we check this and raise the exception. Since I'm just starting out in Python, I don't know if there are thread or other issues with this. Comments would be welcome. Rich. -- Emerging Technologies, Red Hat http://et.redhat.com/~rjones/ 64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421 "[Negative numbers] darken the very whole doctrines of the equations and make dark of the things which are in their nature excessively obvious and simple" (Francis Maseres FRS, mathematician, 1759)

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[Libvir] [PATCH] Xen capabilities does not detect PAE properly
by Richard W.M. Jones 23 Mar '07

23 Mar '07

-- Emerging Technologies, Red Hat http://et.redhat.com/~rjones/ 64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421 "[Negative numbers] darken the very whole doctrines of the equations and make dark of the things which are in their nature excessively obvious and simple" (Francis Maseres FRS, mathematician, 1759)

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