RISC-V With Linux 5.19 Allows Running RV32 32-bit Binaries On RV64, Adds Svpbmt

Written by Michael Larabel in RISC-V on 1 June 2022 at 03:00 AM EDT. 10 Comments
On Tuesday the RISC-V architecture changes were merged into the in-development Linux 5.19 kernel with several new features in tow.

As previously covered, RISC-V with Linux 5.19 brings the new "compat" subsystem for running 32-bit binaries on 64-bit kernels. This RV32 on RV64 support is interesting since the Linux kernel has always catered to 64-bit RISC-V and not much in the way of modern RV32 usage I am aware of at least where someone would be chasing mainline Linux usage.

The other big change on the RISC-V front this cycle is Svpbmt extension support for Supervisor-Mode: Page-Based Memory Types. RISC-V's Svpbmt allows for memory attributes to be encoded directly in pages. See the riscv-isa-manual for more details.

The RISC-V code for Linux 5.19 also adds support for kexec_file_load as the newer Kexec system call that is file-based and relies on FDs being added for the kernel and initramfs. There is also a new ticket-based spinlock system and other smaller fixes.

More details on the RISC-V changes premiering in Linux 5.19 this summer 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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