Bug 216545

Summary:	Add an option to disable sv57 support
Product:	Platform Specific/Hardware	Reporter:	Felix Yan (felixonmars)
Component:	Other	Assignee:	platform_other
Status:	NEW ---
Severity:	normal	CC:	CoelacanthusHex
Priority:	P1
Hardware:	RISC-V
OS:	Linux
Kernel Version:	5.18,5.19,6.0,6.1	Subsystem:
Regression:	No	Bisected commit-id:

Description Felix Yan 2022-10-01 09:59:47 UTC

Since Linux 5.18, sv57 was added for 64-bit RISC-V architecture. Since sv57 is already supported as SATP mode in qemu-system-riscv64 too, Linux uses sv57 automatically and there is no easy option to disable it. This unfortunately breaks userspace programs as at least OpenJDK and v8 still have no support for this mode.

Considering that userspace programs still need significant time to adapt, it is beneficial to provide an option to disable kernel support for sv57 and build distribution kernels with it.

(Ubuntu already started to patch their kernel for this: http://sprunge.us/WGq6Pm and will most likely disable sv57 for kinetic.)