AMD Polaris Support Lands In Mesa's RadeonSI Gallium3D Driver

[phoronix]

Phoronix: AMD Polaris Support Lands In Mesa's RadeonSI Gallium3D Driver

While AMD just open-sourced their next-gen Polaris graphics driver code this week, changes have already landed in LLVM and this morning the Mesa/Gallium3D modifications necessary have landed in mainline Mesa...

http://www.phoronix.com/scan.php?page=news_item&px=AMD-Polaris-In-Mesa

[VikingGe]

while the majority of the hardware bring-up is within the AMDGPU DRM kernel driver and that's not coming until the Linux 4.7 kernel cycle.

So that basically means that we'll have full Polaris support by the end of July, maybe August. Sounds fair.

[FireBurn]

If it's non invasive then it might appear in 11.2.1

[bridgman]

My impression is "superset" accepting existing 1.2 ISA but I haven't had a chance to look closely.

[marek]

It now seems to me that, basically, Polaris instruction set is equal to GCN1.2 or a superset of GCN1.2. Binary code generated for GCN1.2 might run unmodified on Polaris GPUs. Can AMD confirm this if possible? bridgman

Yes, that's correct. If you have old LLVM without Polaris support, Polaris will still work, because Mesa will use shader binaries for Tonga. In a nutshell, you don't need new LLVM.

[Adarion]

First: Very glad to see this progress. Seems like Polaris is actually going to be quite well supported by the freedom driver at launchday / when HW hits the streets.

Well, also from the other additions, it was mentioned that some changes aren't that huge. So I wonder, cause I thought Polaris would be the big new thing. But then, a lot of similarities seem to be with the current GCN generation(s). On the other hand that means faster Linux support since it doesn't need too much coding for a new HW. Or could it be that the HW is different but presents itself to the outside similar to the previous generations (like x86 CPUs that grew over time but still can execute ancient code that was made in 8086 times)?

[bridgman]

Or could it be that the HW is different but presents itself to the outside similar to the previous generations (like x86 CPUs that grew over time but still can execute ancient code that was made in 8086 times)?

This is my understanding, although I only looked at Polaris 10.

[dragorth]

First: Very glad to see this progress. Seems like Polaris is actually going to be quite well supported by the freedom driver at launchday / when HW hits the streets.

Well, also from the other additions, it was mentioned that some changes aren't that huge. So I wonder, cause I thought Polaris would be the big new thing. But then, a lot of similarities seem to be with the current GCN generation(s). On the other hand that means faster Linux support since it doesn't need too much coding for a new HW. Or could it be that the HW is different but presents itself to the outside similar to the previous generations (like x86 CPUs that grew over time but still can execute ancient code that was made in 8086 times)?

So, first, I don't work for AMD.

Polaris is the first AMD GPU on the new 14nm process. This allows them to put more logic on a smaller chip. So, even if they didn't change anything to the previous GCN design, Polaris offers significant benefits in terms of power consumption and compute increase.

AMD has changed things to work better under this new process. It is, however, a GCN architecture, meaning, like x86, in general it works the same way as previous chips. This doesn't mean they didn't add new features. Intel adds new features all the time. Old code still runs on it. New code can take advantage of the new features.

Also keep in mind that GPUs in general are maturing as a technology, Most of the benefits you get from adding more of what are essentially highly parallel math machines. These can change underneath and still wouldn't change the code that runs on them.

[duby229]

....... (like x86 CPUs that grew over time but still can execute ancient code that was made in 8086 times)?

OT: Well actually the best you can hope for is 486 code if you are in legacy mode running a protected mode operating system. It may be possible in some scenarios to do a context switch to real mode and then run 386 code, but i'm not 100% sure on that.

EDIT: Yes, you can run 386 code in dos or other real mode OSes. Not 286 code though, because real mode is different between them.

[SystemCrasher]

Finally AMD has got very close to this elusive milestone: opensource support even before HW release. Whatever, it counts as a reason to buy AMD GPUs. Too bad it seems it wouldn't made it into ubuntu 16.04 LTS, which is due soon (tm).