The following xmllint XPath query will pull out the name of the backing file for a VM named fedora-server-36 and an external snapshot named fedora-36-post-install,
virsh snapshot-dumpxml fedora-server-36 fedora-server-36-post-install | xmllint --xpath "string(//domainsnapshot/disks/disk[@snapshot='external']/source/@file)" - |
The string function extracts the attribute value.
This value can be used in the process of using or deleting the snapshot.
I had a bug in my OpenGL program. Here was the original code:
for (Orbitor o : orbitors){ o.calculate_position(); } |
and here was the working version
for (std::vector<Orbitor>::iterator it = orbitors.begin() ; it != orbitors.end(); ++it) { it->calculate_position(); } |
The processes of development, installation, testing, and debugging of software all benefit from the use of a virtual machines. If you are working in a Linux based infrastructure, you have access to the virtual machine management on your system. There are a handful of related technologies that all work together to help you get your work done.
Continue readingNow that I can build my app with Autotools, I want to make it work with conan. In my head, I have conan mapped to projects like cargo in rust and pip in Python. However, C++ has a far less homogenized toolchain, and I expect things are going to be more “how to make it work for you.” I started with Autotools to minimize that.
Continue readingIn a science fiction game I play, we often find ourselves asking “which side of the Sun is Mars from the Earth right now?” Since this is for a game, the exact distance is not important, just “same side” or “90 degrees ahead” is a sufficient answer. But “right now” actually means a couple hundred years in the future.
Perfect problem to write a little code to solve. Here’s what it looks like.
Continue readingIn a recent article, I saw yet another example of using grep to pull information out of xml, and then to manually look for a field. However, XML is structured, and with XPath, we can pull out exactly what we need.
virsh dumpxml fedora-server-36 | xmllint --xpath "//domain/devices/disk[@device='disk']" - |
That will produce output like this:
<disk type="file" device="disk"> <driver name="qemu" type="qcow2" discard="unmap"/> <source file="/var/lib/libvirt/images/fedora-server-36.qcow2"/> <target dev="vda" bus="virtio"/> <address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/> </disk> |
Note that I did more in my XPath than required by the original article. I wanted to show an example of querying based on an attribute inside the selected node.
Update: Here is an example for what is done later in the article: pull the path out of the pool xml.
virsh pool-dumpxml default | xmllint --xpath "//pool/target/path/text()" - /var/lib/libvirt/images |
I have an Ampere Altra-Max/INGRASYS Yushan Server System running Centos 8 stream.
Because we are a chip manufacteror, we don’t sell end systems, we provide a reference platform that is a starting point for our customers to make a product. This leads to bizarre set of internal versus external names. One thing that you can rely on, however, is the identifier of the processor itself:
# cat /proc/cpuinfo
processor : 0
BogoMIPS : 50.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp ssbs
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x3
CPU part : 0xd0c
CPU revision : 1
...
TO make this readable, use the utility lscpu:
[root@eng14sys-r
111 ~]# lscpu
Architecture: aarch64
Byte Order: Little Endian
CPU(s): 80
On-line CPU(s) list: 0-79
Thread(s) per core: 1
Core(s) per socket: 80
Socket(s): 1
NUMA node(s): 1
Vendor ID: ARM
BIOS Vendor ID: Ampere(R)
Model: 1
Model name: Neoverse-N1
BIOS Model name: Ampere(R) Altra(R) Processor
Stepping: r3p1
CPU max MHz: 3000.0000
CPU min MHz: 1000.0000
BogoMIPS: 50.00
L1d cache: 64K
L1i cache: 64K
L2 cache: 1024K
NUMA node0 CPU(s): 0-79
Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp ssbs
I want to build the latest Linus-repo Linux Kernel and run it on the server. Here’s the steps I went through.
Continue readingThe command to run the formatting tests for the keystone project is:
tox -e pe8
Running this on Fedora35 failed for me with this error:
Continue readingI got keystone in my Bifrost install to talk via LDAP to our Freeipa server. Here’s what I had to do.
Continue readingTo make the AARCH64 ipxe process work using bifrost, I had to
git clone https://github.com/ipxe/ipxe.git cd ipxe/src/ make bin-arm64-efi/snponly.efi ARCH=arm64 sudo cp bin-arm64-efi/snponly.efi /var/lib/tftpboot/ipxe.efi |
This works for the Ampere reference implementation servers that use a Mellanox network interface card, which supports (only) snp.