Newer Loongson 3A Variant Being Supported By Linux 5.5 Along With The SGI Octane

Written by Michael Larabel in Hardware on 27 November 2019 at 01:00 AM EST. 1 Comment
As covered earlier this month, the next version of the Linux kernel is finally offering mainline support for SGI's Octane / Octane II MIPS workstations from the SGI IRIX days about two decades ago. Not only is the vintage SGI IP30 hardware seeing mainline kernel support, but there is other new MIPS hardware support too.

Complementing the SGI Octane support as part of the Linux 5.5 MIPS updates is also supporting the Loongson 3A R4 variant, a newer version compared to what the kernel already supported on the Loongson front, the Chinese MIPS64 CPUs.

The 3A R4 model is also known as the Loongson-3A4000 and builds upon earlier revisions while adding MSA and VZ extensions, supporting CPU config and control/status register extensions, 64 entries of the vTLB, 2048 entries of the fTLB, and other incremental additions to Loongson. The 3A4000 model is this year's Loongson processors revision and is clocked between 1.8~2.0GHz while being a quad-core part leveraging the MIPS64r5 revision. It's still fabbed on a 28nm process like the third revision while having a configurable TDP from 40 to 80 Watts.

We're waiting to see new Loongson benchmark results on to get a better idea for the performance but at least with earlier revisions they were well behind even generations old AMD/Intel x86_64 CPUs and 64-bit ARM CPUs for that matter too.

The Linux support patches in Linux 5.5 for bringing up the Loongson 3A4000 do come from the vendor themselves, Lemote.

Other MIPS changes beyond SGI Octane and Loongson 3A R4 enablement is support for KCOV code coverage support, support for building with FORTIFY_SOURCE enabled, support for MediaTek MT7688 GARDENA smart gateway platforms, and improvements for the existing SGI IP27 Origin 2 support.
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