RISC-V specifies multiple sizes for addressable memory and Linux probes for
the machine's support at startup via the satp CSR register (done in
csr.c:validate_vm).
As per the specification, sv64 must support sv57, which in turn must
support sv48...etc. So we can restrict machine support by simply setting the
"highest" supported mode and the bare mode is always supported.
You can set the satp mode using the new properties "sv32", "sv39", "sv48",
"sv57" and "sv64" as follows:
-cpu rv64,sv57=on # Linux will boot using sv57 scheme
-cpu rv64,sv39=on # Linux will boot using sv39 scheme
-cpu rv64,sv57=off # Linux will boot using sv48 scheme
-cpu rv64 # Linux will boot using sv57 scheme by default
We take the highest level set by the user:
-cpu rv64,sv48=on,sv57=on # Linux will boot using sv57 scheme
We make sure that invalid configurations are rejected:
-cpu rv64,sv39=off,sv48=on # sv39 must be supported if higher modes are
# enabled
We accept "redundant" configurations:
-cpu rv64,sv48=on,sv57=off # Linux will boot using sv48 scheme
And contradictory configurations:
-cpu rv64,sv48=on,sv48=off # Linux will boot using sv39 scheme
Co-Developed-by: Ludovic Henry <ludovic@rivosinc.com>
Signed-off-by: Ludovic Henry <ludovic@rivosinc.com>
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Message-ID: <20230303131252.892893-4-alexghiti@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
6f23aaeb9b