Re: [PATCH 1/2] hw/char/riscv_htif: Fix printing of console characters on big endian hosts

[Alistair Francis]

On Fri, Jul 21, 2023 at 7:48 PM Thomas Huth <thuth@redhat.com> wrote:
>
> The character that should be printed is stored in the 64 bit "payload"
> variable. The code currently tries to print it by taking the address
> of the variable and passing this pointer to qemu_chr_fe_write(). However,
> this only works on little endian hosts where the least significant bits
> are stored on the lowest address. To do this in a portable way, we have
> to store the value in an uint8_t variable instead.
>
> Fixes: 5033606780 ("RISC-V HTIF Console")
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  hw/char/riscv_htif.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c
> index 37d3ccc76b..f96df40124 100644
> --- a/hw/char/riscv_htif.c
> +++ b/hw/char/riscv_htif.c
> @@ -232,7 +232,8 @@ static void htif_handle_tohost_write(HTIFState *s, 
> uint64_t val_written)
>              s->tohost = 0; /* clear to indicate we read */
>              return;
>          } else if (cmd == HTIF_CONSOLE_CMD_PUTC) {
> -            qemu_chr_fe_write(&s->chr, (uint8_t *)&payload, 1);
> +            uint8_t ch = (uint8_t)payload;
> +            qemu_chr_fe_write(&s->chr, &ch, 1);
>              resp = 0x100 | (uint8_t)payload;
>          } else {
>              qemu_log("HTIF device %d: unknown command\n", device);
> --
> 2.39.3
>
>