Specify --xz explicitly when calling dracut to make initrd.

[masteryyh]

Problem:

By default dracut uses Zstandard to compress initrd, and we're trying to use xzcat to decompress initrd which makes kdump.service fail to start.

Solution:

Add --xz when calling dracut to use xz compression.

Related Issue:
harvester/harvester#3928

Test plan:

1. Build an ISO from this branch and deploy;
2. Select debug mode when booting;
3. After booted up, use command systemctl status kdump.service to confirm kdump.service is up and running;
4. After kdump.service exited, use command echo c > /proc/sysrq-trigger to trigger a kernel crash manually;
5. The system should reboot automatically and a progress bar (sort of) of kernel dump should show up;
6. After rebooted, select debug mode again, and see if anything under /var/crash is generated.

[bk201]

LGTM, Thanks!

[Vicente-Cheng]

LGTM!

[bk201]

@Mergifyio backport v1.2

[mergify]

backport v1.2

✅ Backports have been created

• #522 Specify --xz explicitly when calling dracut to make initrd. (backport #519) has been created for branch v1.2

[bk201]

@Mergifyio backport v1.1

[mergify]

backport v1.1

✅ Backports have been created

• #523 Specify --xz explicitly when calling dracut to make initrd. (backport #519) has been created for branch v1.1