| Message ID | 20240407213236.2121592-1-christoph.muellner@vrull.eu (mailing list archive) |
|---|---|
| Headers | show |
| Series | RISC-V: Test th.sxstatus.MAEE bit before enabling MAEE | expand |
Hello: This series was applied to riscv/linux.git (fixes) by Palmer Dabbelt <palmer@rivosinc.com>: On Sun, 7 Apr 2024 23:32:34 +0200 you wrote: > Currently, the Linux kernel suffers from a boot regression when running > on the c906 QEMU emulation. Details have been reported here by Björn Töpel: > https://lists.gnu.org/archive/html/qemu-devel/2024-01/msg04766.html > > The main issue is, that Linux enables XTheadMae for CPUs that have a T-Head > mvendorid but QEMU maintainers don't want to emulate a CPU that uses > reserved bits in PTEs. See also the following discussion for more > context: > https://lists.gnu.org/archive/html/qemu-devel/2024-02/msg00775.html > > [...] Here is the summary with links: - [v3,1/2] riscv: thead: Rename T-Head PBMT to MAE https://git.kernel.org/riscv/c/6179d4a21300 - [v3,2/2] riscv: T-Head: Test availability bit before enabling MAE errata https://git.kernel.org/riscv/c/65b71cc35cc6 You are awesome, thank you!
Currently, the Linux kernel suffers from a boot regression when running on the c906 QEMU emulation. Details have been reported here by Björn Töpel: https://lists.gnu.org/archive/html/qemu-devel/2024-01/msg04766.html The main issue is, that Linux enables XTheadMae for CPUs that have a T-Head mvendorid but QEMU maintainers don't want to emulate a CPU that uses reserved bits in PTEs. See also the following discussion for more context: https://lists.gnu.org/archive/html/qemu-devel/2024-02/msg00775.html This series renames "T-Head PBMT" to "MAE"/"XTheadMae" and only enables it if the th.sxstatus.MAEE bit is set. The th.sxstatus CSR is documented here: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadsxstatus.adoc XTheadMae is documented here: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmae.adoc The QEMU patch to emulate th.sxstatus with the MAEE bit not set is here: https://lore.kernel.org/all/20240329120427.684677-1-christoph.muellner@vrull.eu/ After applying the referenced QEMU patch, this patchset allows to successfully boot a C906 QEMU system emulation ("-cpu thead-c906"). Changes in v3: * Rename to MAE instead of MAEE Changes in v2: * use th.sxstatus.MAEE instead of th.mxstatus.MAEE Christoph Müllner (2): riscv: thead: Rename T-Head PBMT to MAE riscv: T-Head: Test availability bit before enabling MAE errata arch/riscv/Kconfig.errata | 8 ++++---- arch/riscv/errata/thead/errata.c | 24 +++++++++++++++--------- arch/riscv/include/asm/errata_list.h | 20 ++++++++++---------- 3 files changed, 29 insertions(+), 23 deletions(-)