Re: [PATCH 07/12] hw/char: riscv_htif: Support console output via proxy syscall

[Daniel Henrique Barboza]

On 12/27/22 03:48, Bin Meng wrote:
> At present the HTIF proxy syscall is unsupported. On RV32, only
> device 0 is supported so there is no console device for RV32.
> The only way to implement console funtionality on RV32 is to
> support the SYS_WRITE syscall.
>
> With this commit, the Spike machine is able to boot the 32-bit
> OpenSBI generic image.
>
> Signed-off-by: Bin Meng <bmeng@tinylab.org>
> ---

Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

>   hw/char/riscv_htif.c | 17 ++++++++++++++++-
>   1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c
> index 3bb0a37a3e..1477fc0090 100644
> --- a/hw/char/riscv_htif.c
> +++ b/hw/char/riscv_htif.c
> @@ -48,6 +48,9 @@
>   #define HTIF_CONSOLE_CMD_GETC   0
>   #define HTIF_CONSOLE_CMD_PUTC   1
>   
> +/* PK system call number */
> +#define PK_SYS_WRITE            64
> +
>   static uint64_t fromhost_addr, tohost_addr;
>   static int address_symbol_set;
>   
> @@ -165,7 +168,19 @@ static void htif_handle_tohost_write(HTIFState *s, uint64_t val_written)
>                   int exit_code = payload >> 1;
>                   exit(exit_code);
>               } else {
> -                qemu_log_mask(LOG_UNIMP, "pk syscall proxy not supported\n");
> +                uint64_t syscall[8];
> +                cpu_physical_memory_read(payload, syscall, sizeof(syscall));
> +                if (syscall[0] == PK_SYS_WRITE &&
> +                    syscall[1] == HTIF_DEV_CONSOLE &&
> +                    syscall[3] == HTIF_CONSOLE_CMD_PUTC) {
> +                    uint8_t ch;
> +                    cpu_physical_memory_read(syscall[2], &ch, 1);
> +                    qemu_chr_fe_write(&s->chr, &ch, 1);
> +                    resp = 0x100 | (uint8_t)payload;
> +                } else {
> +                    qemu_log_mask(LOG_UNIMP,
> +                                  "pk syscall proxy not supported\n");
> +                }
>               }
>           } else {
>               qemu_log("HTIF device %d: unknown command\n", device);