Does Talos support real-time kernel

[yingwana3]

Hi, all

We need to run time-sensisive workload on Talos. Is there any document for changing default kernel to rt-kernel? Besides, how can we change kernel cmaline parameters after the cluster is installed. We try to modify the controlplane.yaml on extraKernelArgs part and re-apply the config, but talosctl cat /proc/cmdline shows no change at all.

Thanks

[smira]

Talos officially supports only a single Linux kernel it was tested with. You can build Talos with your kernel image and use it.

extraKernelArgs are part of the install section, so they are only applied atm when you do an upgrade (or fresh install), so workaround is to perform an upgrade to the same version of Talos, e.g. talosctl upgrade -n <node> --preserve -i ghcr.io/siderolabs/installer:v1.4.6

[frezbo]

creating state directory in "/root/.talos/clusters/talos-default" well this path specifically

[yingwana3]

Hi, attach thie log info, please help to have a look.

cat dhcpd.log
[dhcpv4] 2023/07/17 00:10:58 Server listening on 0.0.0.0:67
[dhcpv4] 2023/07/17 00:10:58 Ready to handle requests

cat lb.log
2023/07/17 00:10:58 healthcheck failed for "10.5.0.2:6443": dial tcp 10.5.0.2:6443: i/o timeout
2023/07/17 00:10:59 healthcheck failed for "10.5.0.2:6443": dial tcp 10.5.0.2:6443: i/o timeout
2023/07/17 00:11:00 healthcheck failed for "10.5.0.2:6443": dial tcp 10.5.0.2:6443: i/o timeout
2023/07/17 00:11:01 healthcheck failed for "10.5.0.2:6443": dial tcp 10.5.0.2:6443: i/o timeout
2023/07/17 00:11:02 healthcheck failed for "10.5.0.2:6443": dial tcp 10.5.0.2:6443: connect: no route to host

cat talos-default-controlplane-1.log
starting /usr/bin/qemu-system-x86_64 with args:
-m 2048 -smp cpus=2 -cpu max -nographic -netdev tap,id=net0,ifname=tap0,script=no,downscript=no -device virtio-net-pci,netdev=net0,mac=42:20:90:6b:6b:33 -device virtio-rng-pci -device virtio-balloon,deflate-on-oom=on -monitor unix:/root/.talos/clusters/talos-default/talos-default-controlplane-1.monitor,server,nowait -no-reboot -boot order=cn,reboot-timeout=5000 -smbios type=1,uuid=8429c8e3-e53f-4048-84bd-c6f5d1fbaca7 -drive format=raw,if=virtio,file=/root/.talos/clusters/talos-default/talos-default-controlplane-1-0.disk,cache=unsafe -machine q35,accel=kvm -drive file=/root/.talos/clusters/talos-default/talos-default-controlplane-1-flash0.img,format=raw,if=pflash -kernel _out/vmlinuz-amd64 -initrd _out/initramfs-amd64.xz -append init_on_alloc=1 slab_nomerge pti=on consoleblank=0 nvme_core.io_timeout=4294967295 printk.devkmsg=on ima_template=ima-ng ima_appraise=fix ima_hash=sha512 console=ttyS0 reboot=k panic=1 talos.shutdown=halt talos.platform=metal talos.config=http://10.5.0.1:35669/config.yaml
qemu: could not open kernel file '_out/vmlinuz-amd64': No such file or directory
process exited with error exit status 1

cat talos-default-worker-1.log
starting /usr/bin/qemu-system-x86_64 with args:
-m 2048 -smp cpus=2 -cpu max -nographic -netdev tap,id=net0,ifname=tap0,script=no,downscript=no -device virtio-net-pci,netdev=net0,mac=8a:0e:62:0d:f1:74 -device virtio-rng-pci -device virtio-balloon,deflate-on-oom=on -monitor unix:/root/.talos/clusters/talos-default/talos-default-worker-1.monitor,server,nowait -no-reboot -boot order=cn,reboot-timeout=5000 -smbios type=1,uuid=4a195349-7561-43c3-8270-34bd08775c3e -drive format=raw,if=virtio,file=/root/.talos/clusters/talos-default/talos-default-worker-1-0.disk,cache=unsafe -machine q35,accel=kvm -drive file=/root/.talos/clusters/talos-default/talos-default-worker-1-flash0.img,format=raw,if=pflash -kernel _out/vmlinuz-amd64 -initrd _out/initramfs-amd64.xz -append init_on_alloc=1 slab_nomerge pti=on consoleblank=0 nvme_core.io_timeout=4294967295 printk.devkmsg=on ima_template=ima-ng ima_appraise=fix ima_hash=sha512 console=ttyS0 reboot=k panic=1 talos.shutdown=halt talos.platform=metal talos.config=http://10.5.0.1:35477/config.yaml
qemu: could not open kernel file '_out/vmlinuz-amd64': No such file or directory
process exited with error exit status 1

[frezbo]

as the error says you don;t have the kernel file:

qemu: could not open kernel file '_out/vmlinuz-amd64': No such file or directory

you'd have to either copy kernel and initramfs to _out or run make kernel initramfs which would copy the file.

[yingwana3]

Hi, frezo

As we are totally new to talos. Whether it's possible to provide some guidance on how to build a talos-rt-kernel.iso (we can customize the realtime kernel version). Currently, we can only install talos successfully with this way.

[frezbo]

if you have the custom kernel already built you can place that under _out/vmlinuz-amd64 and run make initramfs to create the initramfs and test