[arch-proaudio] Kernel with extended RT capabilities

[Ralf Mardorf]

Hi,

my apologies for breaking the thread. I subscribed a few minutes ago
and read the archive, IOW I didn't receive a mail with the required
header for this reply.

In my experiences it's wise to keep several rt patched kernel
versions, just in case a patched kernel should cause issues.

The mainline/stable as well as the longterm rt kernel from AUR as well
as those provided by the Arch audio repo a while back, not always
worked with e.g. some old AMD machines or at least not without a
tailored config.

For my new Intel machine I currently try to keep up with the latest
patch from the 4.11/, 4.13/ and 4.14/ tree [1].

I didn't update 4.14 to the current version, since there's is an issue
with building the modules for the version of virtualbox I'm using.

For the Arch repository it wouldn't be as easy to maintain a rt
patched kernel, as it is to provide a vanilla kernel with a config that
is good for pro-audio, when booted with threadirqs. Ubuntu provides a
quasi vanilla kernel "lowlatency", other than linux from Arch's core,
it comes with the feature, that it doesn't require a bootloader entry
"treadirqs" [3].

Btw. it wouldn't be possible to stay in sync with linux and linux-rt
from Arch's core, since the rt project doesn't provide a patch for each
available kernel release.

Regards,
Ralf

[1]
[root at moonstudio weremouse]# systemd-nspawn -qD /mnt/archlinux/ 2>/dev/null pacman -Q linux-rt{,-cornflower,-pussytoes}|awk '{print $2}'
4.13.13_rt5-1
4.11.12_rt16-1
4.14_rt1-1

[2]
[root at moonstudio weremouse]# apt list -qq linux-lowlatency
linux-lowlatency/xenial-updates,xenial-security,now 4.4.0.101.106 amd64 [installed]

[3]
[root at moonstudio weremouse]# grep threadirqs /mnt/archlinux/boot/syslinux/syslinux.cfg
    MENU LABEL Arch Linux ^threadirqs
    APPEND root=LABEL=archlinux ro threadirqs