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Re: [Libvir] BUG: virDomainLookupByID fails after XenStore path discovery
by Jim Fehlig 05 Apr '06

05 Apr '06

>>> "Bryan D. Payne" <bryan(a)thepaynes.cc> 04/04/06 6:23 PM >>> >> I'm just not seeing it included in path returned by >> xs_get_domain_path(), only see /local/domain/<num> > For what it's worth, I was trying to put a patch together for this, >but I kept getting memory corruption errors. I was trying to access >the name through the xenstore as shown below... > > /* lookup is easier with the Xen store so try it first */ > if (conn->xshandle != NULL) { > char *namepath = NULL; > path = xs_get_domain_path(conn->xshandle, (unsigned int) id); > namepath = strdup(path); > strcat(namepath, "/name"); > name = xs_read(conn->xshandle, NULL, namepath, NULL); > if (namepath) free(namepath); > } My brain is not working today :-). Don't know why I didn't consider xs_read(). I'll fix up your patch and test/submit it tomorrow. I think the only problem is concatenating "/name" on the end of namepath, which has only been allocated enough memory to hold path via strdup(). Thanks, Jim

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[Libvir] BUG: virDomainLookupByID fails after XenStore path discovery
by Bryan D. Payne 05 Apr '06

05 Apr '06

I just updated to the latest CVS version of libvir. It looks like there's a bug in virDomainLookupByID. The behavior that I'm seeing is that the path variable is set and so the code never enters the block to find the value for name. Therefore, at the end of the function, the condition (ret->name == NULL) is true and it jumps into the error code and returns NULL. If I comment out the code that sets the path variable, things seem to work normally. Although, I presume that the idea was to extract the name from the path information... -bryan - Bryan D. Payne Graduate Student, Computer Science Georgia Tech Information Security Center http://www.bryanpayne.org

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[Libvir] Change of server
by Daniel Veillard 03 Apr '06

03 Apr '06

So far libvirt.org was hosted on my home server (IP 82.67.66.12), but I really needed to fix this as my home ADSL connectivity isn't that great. I moved all services to a new server (colocated on the same box as xmlsoft.org in a public research institute here in France), hopefully the transition to this new server (IP 194.199.20.115) will be transparent as DNS changes propagates, but some of you mays still access the old services for a little while. Tell me if you experience troubles with the new server, and if you don't see updates from libvirt.org CVS that may be related still using the old server. Hopefully bandwidth and relibaility should be quite higher now, thanks, Daniel -- Daniel Veillard | Red Hat http://redhat.com/ 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] Patch to make reading of HTTP response more efficient
by Daniel P. Berrange 30 Mar '06

30 Mar '06

When processing the header of HTTP responses from Xend, libvirt currently reads data a single byte at a time. Since its using lowlevel UNIX read() function there is no buffering, which results in a large number of system calls. The attached patch re-factors the code so that it reads data in 4k chunks whenever possible. Since most rsponses are < 4k in size processing the response now only takes two read() syscalls, rather than several hundred. Of course most (90%) of the CPU overhead is still on the Xend/XenStored end of the channel, but that's out of our control until the XML-RPC API comes along. Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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[Libvir] unchecked `malloc' calls
by Jim Meyering 30 Mar '06

30 Mar '06

Hello, In browsing through the code, I noticed that there are many places in which the code doesn't check for malloc returning NULL. E.g., ./virsh.c: ids = malloc(sizeof(int) * maxid); ./virsh.c- virConnectListDomains(ctl->conn, &ids[0], maxid); ./virsh.c: *res = malloc(sz + 1); ./virsh.c- memcpy(*res, tkstr, sz); ./virsh.c: res = malloc(strlen(name) + 3); ./virsh.c- sprintf(res, "--%s", name); ./xmlrpc.c: buf = malloc(sizeof(*buf)); ./xmlrpc.c- buf->size = 1024; ./xmlrpc.c: xmlRpcValueDictElementPtr ret = malloc(sizeof(*ret)); ./xmlrpc.c- xmlNodePtr cur; ./xmlrpc.c- ./xmlrpc.c- memset(ret, 0, sizeof(*ret)); At first, seeing so many, I thought there must be a wrapper that handles the case of a NULL return value. But there are many places where the code *does* check for NULL. This may be a clue. Maybe it's planned... ./libvirt.c: * TODO: ... ./libvirt.c: * - memory wrappers for malloc/free ? Jim

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[Libvir] RFC: requesting APIs for host physical resource discovery
by Daniel P. Berrange 29 Mar '06

29 Mar '06

The current libvirt APIs allow the host's physical resources to be split up and allocated to guest domains, however, there is no way to discover what the available host resources actually are. Thus I would like to suggest the inclusion of new APIs to enable host resource discovery. As a starting point I'd like to be able to query the following information: * Number of physical CPUs - ability to enumerate the CPUs in the host, both those currently present, and theoretical maximum (to take account of hotplug). * Amount of RAM - actual physical RAM present, and that available for guest usage (eg discounting that reserved by a hypervisor or equiv) * CPU relationship - ie ability to distinguish between CPUs which are hyperthread siblings, on same core, or on separate sockets Alonside these basic queries it would be desirable to add a further resource resource management API to allow for setting of a guest domain's CPU affinity. ie ability control what CPUs the VMM is allowed to schedule a domain on. Once this first basic set of caapbilties for resource discovery are provided for, then I believe it will be neccessary to provide some more advanced queries, in particular: * NUMA topology - ability to enumerate NUMA nodes, the CPUs associated with each node & the RAM range mapped to that node Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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[Libvir] python/libvir.html example needs adjustment
by Jim Meyering 28 Mar '06

28 Mar '06

Hello, Trying a variant of this example from python/libvir.html: import libvirt import sys conn = libvirt.openReadOnly(None) if conn == None: print 'Failed to open connection to the hypervisor' sys.exit(1) dom0 = conn.lookupByName("Domain-0") if dom0 == None: print 'Failed to find the main domain' sys.exit(1) print "Domain 0: id %d running %s" % (dom0.ID(), dom0.OSType()) print dom0.info() I found that conn.lookupByName throws an exception when the specified name is not found. If the example is just out of date, it should use try:/except: instead of comparing dom0 to None, shouldn't it? You can demonstrate it like this: $ python -c 'import libvirt; libvirt.openReadOnly(None).lookupByName("x")' libvir: Xen Daemon error : GET operation failed: No such domain x Traceback (most recent call last): File "<string>", line 1, in ? File "/usr/lib/python2.4/site-packages/libvirt.py", line 213, in lookupByName if ret is None:raise libvirtError('virDomainLookupByName() failed') libvirt.libvirtError: virDomainLookupByName() failed [Exit 1] Jim

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[Libvir] use gcc's printf __attribute__
by Jim Meyering 27 Mar '06

27 Mar '06

Hello, I noticed that there are a few printf-like functions here, but that they don't benefit from gcc's format-string vs. arg-type checking. Here's a patch to enable that: However, to make it portable to non-gcc systems, this block of cpp directives needs to go somewhere (maybe libvirt.h?) so it'll be used from both files. #ifndef __attribute__ /* This feature is available in gcc versions 2.5 and later. */ # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5) # define __attribute__(Spec) /* empty */ # endif /* The __-protected variants of `format' and `printf' attributes are accepted by gcc versions 2.6.4 (effectively 2.7) and later. */ # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7) # define __format__ format # define __printf__ printf # endif #endif 2006-03-25 Jim Meyering <jim(a)meyering.net> * src/virsh.c (vshPrint, vshError): Add gcc's __printf__ attribute. * src/xml.h (virBufferVSprintf): Likewise. Index: src/xml.h =================================================================== RCS file: /data/cvs/libvirt/src/xml.h,v retrieving revision 1.3 diff -u -p -r1.3 xml.h --- src/xml.h 15 Mar 2006 12:13:25 -0000 1.3 +++ src/xml.h 25 Mar 2006 10:56:27 -0000 @@ -25,7 +25,8 @@ extern "C" { }; int virBufferAdd(virBufferPtr buf, const char *str, int len); - int virBufferVSprintf(virBufferPtr buf, const char *format, ...); + int virBufferVSprintf(virBufferPtr buf, const char *format, ...) + __attribute__ ((__format__ (__printf__, 2, 3))); char *virDomainParseXMLDesc(const char *xmldesc, char **name); #ifdef __cplusplus Index: src/virsh.c =================================================================== RCS file: /data/cvs/libvirt/src/virsh.c,v retrieving revision 1.21 diff -u -p -r1.21 virsh.c --- src/virsh.c 15 Mar 2006 12:13:25 -0000 1.21 +++ src/virsh.c 25 Mar 2006 10:56:28 -0000 @@ -177,8 +177,8 @@ typedef struct __vshControl { static vshCmdDef commands[]; -static void vshError(vshControl * ctl, int doexit, const char *format, - ...); +static void vshError(vshControl * ctl, int doexit, const char *format, ...) + __attribute__ ((__format__ (__printf__, 3, 4))); static int vshInit(vshControl * ctl); static int vshDeinit(vshControl * ctl); static void vshUsage(vshControl * ctl, const char *cmdname); @@ -198,8 +198,9 @@ static virDomainPtr vshCommandOptDomain( const char *optname, char **name); -static void vshPrint(vshControl * ctl, vshOutType out, const char *format, - ...); +static void vshPrint(vshControl * ctl, vshOutType out, const char *format, ...) + __attribute__ ((__format__ (__printf__, 3, 4))); + ; static const char *vshDomainStateToString(int state);

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[Libvir] Patch for include file syntax
by Daniel P. Berrange 25 Mar '06

25 Mar '06

When doing an out-of-tree build of code which uses virterror.h, one gets a build failure, because when deployed virterror.h lives in subdir of the include directory rather than the top level In file included from Virt.xs:25: /usr/include/libvirt/virterror.h:17:21: error: libvirt.h: No such file or directory In file included from Virt.xs:25: /usr/include/libvirt/virterror.h:62: error: expected specifier-qualifier-list before âvirConnectPtrâ /usr/include/libvirt/virterror.h:122: error: expected â)â before âconnâ /usr/include/libvirt/virterror.h:123: error: expected â)â before âconnâ /usr/include/libvirt/virterror.h:129: error: expected â)â before âconnâ /usr/include/libvirt/virterror.h:132: error: expected â)â before âconnâ This is fixable by making virterror.h use "..." instead of <...> to include libvirt.h. Attaching a patch to fix this Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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[Libvir] Patch for pkg-config file cflags
by Daniel P. Berrange 24 Mar '06

24 Mar '06

The libvirt.pc.in file has an empty field for the cflags variable, so if you install libvirt into any prefix which is not in the compiler's default include file search path the header files won't be found when compiling applications. Attching a patch which corrects the pkg-config file for libvirt Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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