Change Details

Newer versions of QEMU (7.1.0) will append to the riscv,isa property indicating the presence of pseudo-extensions such as Zfencei. This breaks some assumptions about how to parse the string, and triggers a KASSERT about the expected length. For example, what is generated with a default virt instance: cpu@0 { ... riscv,isa = "rv64imafdch_zicsr_zifencei_zba_zbb_zbc_zbs"; } Allocate the buffer for the property dynamically, and stop when we encounter an underscore. This is a stop-gap to quickly fix booting with QEMU, and in our CI. Future changes will be made to handle this better and parse more extensions.

This code was originally written under the assumption that the ISA string would only contain single-letter extensions. The RISC-V specification has extended its description of the format quite a bit, allowing for much longer ISA strings containing multi-letter extension names. Newer versions of QEMU (7.1.0) will append to the riscv,isa property indicating the presence of multi-letter standard extensions such as Zfencei. This triggers a KASSERT about the expected length of the string, preventing boot. Increase the size of the isa array significantly, and teach the code to parse multi-letter extensions, and optional extension version numbers. We currently ignore them completely, but this will change in the future as we start supporting supervisor-level extensions.

Newer versions of QEMU (7.1.0) will append toThis code was originally written under the riscv,isa propertyassumption that the ISA indicating the presence of pseudo-extensions such as Zfenceistring would only contain single-letter extensions. ThisThe RISC-V breaks some assumptions about how to parsespecification has extended its description of the string, and triggers aformat quite a bit, KASSERT about the expected lengthallowing for much longer ISA strings containing multi-letter extension names. For example, what is generated with a default virt instance:Newer versions of QEMU (7.1.0) will append to the riscv,isa property cpu@0 {indicating the presence of multi-letter standard extensions such as ...Zfencei. This triggers a KASSERT about the expected length of the riscv,isa = "rv64imafdch_zicsr_zifencei_zba_zbb_zbc_zbs"; }string, preventing boot. AllocatIncrease the buffer forsize of the property dynamicallyisa array significantly, and stop when weteach the code encounter an underscore.to parse multi-letter extensions, This is a stop-gap to quickly fix booting withand optional extension version QEMU,numbers. and in our CI.We currently ignore them completely, Future changebut this will be made to handle this betterchange in and parse morethe future as we start supporting supervisor-level extensions.