Hi Bin,
On Fri, 2018-12-07 at 06:14 -0800, Bin Meng wrote:
> Implement arch_cpu_init() to do some basic architecture level cpu
> initialization, like FPU enable, etc.
>
> Signed-off-by: Bin Meng <bmeng...@gmail.com>
>
> ---
>
> Changes in v2:
> - use csr_set() to set MSTATUS_FS
> - only enabling the cycle, time, and instret counters
> - change to use satp
>
> arch/riscv/cpu/cpu.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c
> index 3858e51..194799c 100644
> --- a/arch/riscv/cpu/cpu.c
> +++ b/arch/riscv/cpu/cpu.c
> @@ -7,6 +7,7 @@
> #include <cpu.h>
> #include <log.h>
> #include <asm/csr.h>
> +#include <asm/encoding.h>
>
> /*
> * prior_stage_fdt_address must be stored in the data section since
> it is used
> @@ -67,3 +68,21 @@ int arch_early_init_r(void)
>
> return 0;
> }
> +
> +int arch_cpu_init(void)
> +{
> + /* Enable FPU */
> + if (supports_extension('d') || supports_extension('f')) {
supports_extension does not work when running in supervisor mode
(unless BBL is patched). Can we maybe use the CPU driver here?
> + csr_set(MODE_PREFIX(status), MSTATUS_FS);
> + csr_write(fcsr, 0);
> + }
> +
> + /* Enable perf counters for cycle, time, and instret counters
> only */
> + csr_write(MODE_PREFIX(counteren), GENMASK(2, 0));
I would tend to only enable this in mcounteren, so for the supervisor-
mode. Linux can still enable the counters for user-mode if required.
> +
> + /* Disable paging */
> + if (supports_extension('s'))
> + csr_write(satp, 0);
This should only be done, when running in machine mode. In supervisor
mode this would cause issues if we have something other than an
identity-mapping or paging disabled.
Thanks,
Lukas
> +
> + return 0;
> +}
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