Hello, I am new to AMD-Support, and I know you guys don't want to provide any support for for Debian, but in fact my question is not really Debian-specific, but Linux-specific.
I have been using Low-Latency kernel, it means on Debian, you configure the sources yourself and build a kernel-package, pre-built versions are not available.
Changing from open-source Radeon-driver respectively AMD-GPU kernel-driver to FGLRX I found, it is not workable with low-latency-kernel. I wonder why this is the case, because the Low-Latency feature of Linux is in mainline, it is not an external patch, like Realtime-Linux, so it should work probably. I am referring to this kernel-version, currently in Debian stable:
|i A linux-image-3.16.0-4-amd64|
- Linux 3.16 for 64-bit PCs
> State: installed
> Automatically installed: yes
> Version: 3.16.7-ckt11-1+deb8u5
> Priority: optional
> Section: kernel
> Maintainer: Debian Kernel Team <email@example.com>
> Architecture: amd64
> Uncompressed Size: 163 M
> Depends: kmod | module-init-tools, linux-base (>= 3~), debconf (>= 0.5) | debconf-2.0,
> PreDepends: debconf | debconf-2.0
> Recommends: firmware-linux-free (>= 3~), irqbalance
> Suggests: linux-doc-3.16, debian-kernel-handbook, grub-pc | grub-efi | extlinux
> The Linux kernel 3.16 and modules for use on PCs with AMD64, Intel 64 or VIA Nano processors.
> This kernel also runs on a Xen hypervisor. It supports both privileged (dom0) and unprivileged
> (domU) operation.
> Homepage: https://www.kernel.org/
FGLRX for Linux 4.x does not exist yet.
I can give you the configuration, I used, and logfiles but it is probably not necessary, someone there will be able to check 'Low-Latency' instead of 'Voluntary Preemtion' (Desktop), build a kernel-package, I guess, and see for yourselves it is not workable with FGLRX. Or simply try it out on Ubuntu, they provide ready-made low-latency kernels.
I am looking forward to AMD releasing a free and open-source version of OpenCL drivers, currently trying to get started with this.