August 2013 - Libguestfs - libguestfs List Archives

Fedora Rawhide / libguestfs 1.23.14 now enables -cpu host, +kvmclock
by Richard W.M. Jones 15 Aug '13

15 Aug '13

Passing '-cpu host' is meant to cause qemu to pass the same CPUID flags from the host up to the appliance. The major benefit of this is that the appliance can use all CPU features available to optimize eg. checksumming, crypto, RAID XOR operations, zero fill. However in practice this can cause strange problems on some hardware: https://bugzilla.redhat.com/show_bug.cgi?id=870071 This manifests itself as particular operations failing randomly, especially if RAID or crypto is involved. If you enable debugging you would see a kernel stack trace similar to the one shown in the bug above (and possibly many other variations). If you see anything like this, please file a bug. Adding +kvmclock should cause the appliance to use kvm-clock instead of the default (probably tsc). This should improve clock stability on heavily loaded machines, and as far as I know has no downside. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW

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Re: [Libguestfs] Supermin on mageia
by Richard W.M. Jones 15 Aug '13

15 Aug '13

On Thu, Aug 15, 2013 at 11:36:38AM +0800, Joseph Wang wrote: > Hello, > > I'm trying to get supermin to work on mageia and I've run into the > following glitch. Mageia has /etc/init.d as a symlink that is pointing to > /etc/rc.d/init.d and after I generate the appliance and run supermin-helper > I get > > supermin helper [00033ms] finished creating kernel > supermin helper [01415ms] finished mke2fs > supermin helper [01415ms] visiting /usr/lib64/guestfs/supermin.d > supermin helper [01416ms] visiting /usr/lib64/guestfs/supermin.d/base.img > supermin helper [01548ms] visiting /usr/lib64/guestfs/supermin.d/daemon.img > supermin helper [01555ms] visiting /usr/lib64/guestfs/supermin.d/hostfiles > supermin-helper: ext2: parent directory not found: rc.d/init.d: File not > found by ext2_lookup > > What appears to be happening is that supermin-helper is trying to set up > the symlink from init.d to rc.d/init.d before rc.d has been created. > > Do you have any suggestions as to how to handle this? This is a bug in supermin. But as a simple workaround you could create a file which creates the required directory /etc/rc.d/init.d before hostfiles is loaded. Something like this: mkdir -p /tmp/etc/rc.d/init.d cd /tmp find etc | cpio --quiet -o -H newc > /tmp/00-rc.img cp /tmp/00-rc.img /usr/lib64/guestfs/supermin.d/ Note files in supermin.d are visited in lexicographic order. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top

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[PATCH v2 0/4] Experimental User-Mode Linux backend.
by Richard W.M. Jones 09 Aug '13

09 Aug '13

v1 was here: https://www.redhat.com/archives/libguestfs/2013-August/msg00005.html This now works, to some extent. The main problem now is that devices are named /dev/ubd[a-] which of course confuses everything. I'm thinking it may be easier to add a udev rule to rename them. Rich.

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[PATCH 0/4] Not quite working User-Mode Linux backend.
by Richard W.M. Jones 09 Aug '13

09 Aug '13

This is a User-Mode Linux backend for libguestfs. You can select it by doing: export LIBGUESTFS_BACKEND=uml export LIBGUESTFS_QEMU=/path/to/vmlinux Note we're reusing the 'qemu' variable in the handle for convenience. QEmu is not involved when using the UML backend. This almost works. UML itself crashes when the daemon tries to connect to the serial port. I suspect it's because I'm using the 'ssl3=fd:<N>' option. Rich.

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[PATCH] Fix parsing of boot flag in do_part_get_bootable()
by Paul Mackerras 07 Aug '13

07 Aug '13

The code in do_part_get_bootable() assumes that if a partition has the bootable flag set, then that is the only flag. It compares the entire flags field with the string "boot". However, the boot flag isn't always the only flag. For instance, POWER systems typically have a bootable partition of type 0x41 (PPC PReP boot), which parted -m displays as: # parted -m -- f18.img unit b print BYT; /root/f18.img:16106127360B:file:512:512:msdos::; 1:1048576B:5242879B:4194304B:::boot, prep; That is, the flags field contains "boot, prep", and thus libguestfs fails to see that this partition is bootable. Ultimately this causes virt-resize to fail to set the bootable flag on the boot partition of the destination image, resulting in an image that won't boot. This patch fixes the problem by searching for the string "boot" within the flags field, instead of comparing the whole flags field. --- --- libguestfs-1.22.5/daemon/parted.c~ 2013-02-03 00:47:53.000000000 +1100 +++ libguestfs-1.22.5/daemon/parted.c 2013-08-02 11:16:49.921790245 +1000 @@ -628,7 +628,7 @@ if (boot == NULL) return -1; - return STREQ (boot, "boot"); + return strstr (boot, "boot") != NULL; } else { /* Old-style: First look for the line matching "^Number". */

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Re: [Libguestfs] Windows Image File Manipulation
by Richard W.M. Jones 02 Aug '13

02 Aug '13

On Thu, Aug 01, 2013 at 11:31:04PM -0400, Adam Schneider wrote: > Does guestfs for Python support accessing an image file in this manner? Yes. See: http://libguestfs.org/guestfs-python.3.html#example-2:-inspect-a-virtual-ma… + the g.find (or g.find0) API. > Will the mounting capabilities work in Windows? Windows guest or host? Please send all questions to the mailing list. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top

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Re: [Libguestfs] hivex from python
by Richard W.M. Jones 01 Aug '13

01 Aug '13

On Wed, Jul 31, 2013 at 09:13:46PM -0500, Edward wrote: > I plan to do the development in Python and I just can't seem to find enough > documentation or sample code to really get started. If you could send me > some sample code to perform common task or point me in the right direction > it would be most appreciated. Please send questions to the mailing list: https://www.redhat.com/mailman/listinfo/libguestfs You don't need to subscribe. --- It's not clear if your intended program will run in the Windows machine itself, or if you want to edit the registry outside a Windows guest using libguestfs. Anyway, there is one example of using hivex from Python here: https://rwmj.wordpress.com/2010/11/28/use-hivex-from-python-to-read-and-wri… This example is a little bit obsolete (but will still work), because you can now use the hivex API directly via libguestfs which is more efficient. There are also some test programs here written in Python: https://github.com/libguestfs/hivex/tree/master/python/t Using hivex from Python is no different from using it from C, so just follow any C examples and mentally map them into Python, eg: hivex_root(h) ===> h.root Here is the C API documentation: http://libguestfs.org/hivex.3.html Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/

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