RISC-V Gets Sv57-Based Virtual Memory, Other Improvements For Linux 5.18
Written by Michael Larabel in RISC-V on 27 March 2022 at 12:06 PM EDT. 12 Comments
RISC-V --
The RISC-V CPU architecture updates have landed for the in-development Linux 5.18 kernel.

Notable with the RISC-V additions for Linux 5.18 is sv57 support for 5-level page tables. It was just with the prior kernel that sv48 was added for 4-level page tables on RISC-V while this new kernel brings it up to 57-bit page-based virtual memory support for allowing RISC-V systems of the future with even greater memory capacities.

Last year with Linux 5.13 the Microchip PolarFire was added to the mainline kernel while Linux 5.18 is further improving that target. With Linux 5.18 there are improvements for the PolarFire SoC and ICICLE development board that in turn now allow the upstream RISC-V kernel build to run gracefully on the hardware without any extra modifications.

RISC-V with Linux 5.18 also has a new memmove() implementation. The prior memmove() did not properly check memory alignment and could cause the kernel to crash on some systems while elsewhere would just be a sub-optimal performant experience.

Also notable with RISC-V for Linux 5.18 are supporting additional extensions for a "much more useful perf implementation" for those wanting to use the Linux kernel's perf subsystem on RISC-V.

Last but certainly not least is Restartable Sequences "RSEQ" support on RISC-V for what can be a performance win when using the new interfaces.


The RISC-V based SiFive HiFive Unmatched


The full list of RISC-V changes for Linux 5.18 via this Git merge.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

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