'svade' is a RVA22S64 profile requirement, a profile we're going to add
shortly. It is a named feature (i.e. not a formal extension, not defined
in riscv,isa DT at this moment) defined in [1] as:
"Page-fault exceptions are raised when a page is accessed when A bit is
clear, or written when D bit is clear.".
As far as the spec goes, 'svade' is one of the two distinct modes of
handling PTE_A and PTE_D. The other way, i.e. update PTE_A/PTE_D when
they're cleared, is defined by the 'svadu' extension. Checking
cpu_helper.c, get_physical_address(), we can verify that QEMU is
compliant with that: we will update PTE_A/PTE_D if 'svadu' is enabled,
or throw a page-fault exception if 'svadu' isn't enabled.
So, as far as we're concerned, 'svade' translates to 'svadu must be
disabled'.
We'll implement it like 'zic64b': an internal flag that profiles can
enable. The flag will not be exposed to users.
[1] https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231218125334.37184-20-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
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