IBM Deprecating Linux Drivers For CXL Coherent Accelerators & CAPI Flash

[phoronix]

Phoronix: IBM Deprecating Linux Drivers For CXL Coherent Accelerators & CAPI Flash

IBM engineers announced they are deprecating the upstream CXL and CXLFLASH Linux kernel drivers with plans to then remove the drivers from the mainline kernel the following cycle. Before getting too worked up when seeing the "cxl: Deprecate driver" patch, this is about the Coherent Accelerator Processor Interface (CAPI) that predates the Compute Express Link...

https://www.phoronix.com/news/IBM-Deprecates-CXL-CAPI-Flash

[zexelon]

This is surprising! I thought IBM's whole purpose for existing was to never deprecate anything and always maintain 100% backwards compatibility...

Isn't their claim to fame, that you can run System/360 code from the 70s on a modern Z Mainframe with no changes?

[Gamer1227]

This is surprising! I thought IBM's whole purpose for existing was to never deprecate anything and always maintain 100% backwards compatibility...

Isn't their claim to fame, that you can run System/360 code from the 70s on a modern Z Mainframe with no changes?

The System 360 compatibility is for their zOS and only on Z arch, of course Linux is not compatible, their clients that use linux only run new code.

Also it is Power, not focused on backwards compatability

[kylew77]

Isn't this part of those Raptor POWER 9 servers that were released a few years back? I'm sure there are plenty of people still running those!

[Jumbotron]

This is surprising! I thought IBM's whole purpose for existing was to never deprecate anything and always maintain 100% backwards compatibility...

Isn't their claim to fame, that you can run System/360 code from the 70s on a modern Z Mainframe with no changes?

It’s not surprising at all. Every implementation of heterogeneous memory management between chips, chiplet clusters and racks by all the major players, IBM, HP, AMD, ARM and Intel have been given over to the CXL Foundation. One implementation to rule them all. So why should IBM continue to fund development of something that they gave away and is now superseded by a superset of their contribution ? The same hold true for HP’s Gen-Z scheme which is now part of CXL.

[klokik]

Wonder if they are removing this to free up the name and avoid confusions on which CXL certain patch is for.

[kieffer]

I still know several FPGA boards interconnected to power9 using CAPI connectors ... this hardware is not yet 5 years old, so when one sees the development time for FPGA, I find this deprecation a bit early. Not sure I gonna buy any IBM systems in the decades to come.

[lowflyer]

I remember seeing "CAPI" discussed in magazines decades ago. Can somebody name a few devices that still need these drivers?

[bridgman]

I remember seeing "CAPI" discussed in magazines decades ago. Can somebody name a few devices that still need these drivers?

The one that came to mind was the "Summit" supercomputer, which IIRC used CAPI/NVLink between the Power9 CPUs and the NVidia GPUs. Apparently Summit was scheduled for shutdown last month which might explain the timing.

EDIT - seems that IBM also sold POWER8-based servers using CAPI for GPUs and peripherals. Code name was "Minsky" but don't know what the marketing name was.