Thomas Huth's blog

Recently, I needed to debug a problem that only occurred in RHCOS images that are running in secure execution mode on an IBM Z system. Since I don’t have a OCP installation at hand, I wanted to run such an image directly with QEMU or libvirt. This sounded easy at...

A couple of weeks ago, Red Hat Enterprise Linux 9.2 and Red Hat Enterprise Linux 8.8 have been release – time to look at the new features here with regards to KVM virtualization on IBM Z systems. Rebased versions in RHEL 9.2 The KVM code in the 5.14-based kernel of...

For a long time, the QEMU project hosted its git repository on their own server and used Launchpad for tracking bugs. The self-hosting of the git repository caused some troubles, so the project switched the main repository to Gitlab in January 2021. That change of course also triggered the question...

This week, Red Hat Enterprise Linux 9 has been announced, which will also bring us lots of new stuff for our beloved mainframe. First, compared with RHEL 8, a lot of generic packages have been updated, of course. For example, RHEL 9 on IBM Z comes with: Linux kernel 5.14...

This blog is mainly a reminder for myself for the various possibilities to check my shell scripts for portability, but maybe it’s helpful for some other people, too. First, why bother? Well, while bash is the default /bin/sh shell on many rpm-based Linux distributions (so it’s also the default shell...

Starting today, on December 1st, the first door of the QEMU Advent Calendar 2020 can now be opened! The advent calendar reveals a new disk image or something similar for download on each of the first 24 days in December 2020, to create a fun experience for the QEMU community,...

The recent generation of the mainframe (i.e. the z15) has the possibility to run protected KVM guests, so that the administrator of the host LPAR does not have the possibility anymore to read or alter the memory of a guest. This feature is called “Secure Execution” on the IBM Z....

Here’s another bunch of tips for QEMU developer – if you are not working with the QEMU source code, you can certainly ignore this article. Compiling QEMU is a tedious action, since it takes quite some time to compile the whole code base. But with some basic tricks, you can...

A couple of times I already ran into the situation that I wanted to provide a small guest disk image to other people. For example, one time I wanted to provide a test application like LTP to colleagues via a server where I only had some limited disk quota available....