[PATCH v3 1/3] efi_loader: Avoid overwriting previous outputs on console screen clearing

[Simon Glass]

Hi,

On Fri, 4 Nov 2022 at 02:07, Jan Kiszka <jan.kiszka at siemens.com> wrote:
>
> From: Jan Kiszka <jan.kiszka at siemens.com>
>
> Before clearing the screen, ensure that no previous output of firmware
> or UEFI programs will be overwritten on serial devices or other
> streaming consoles. This helps generating complete boot logs.
>
> Tested regarding multi-output against qemu-x86_defconfig.
>
> Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
> ---
>  lib/efi_loader/efi_console.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Please see this thread...some things need to be improved in this area.

https://patchwork.ozlabs.org/project/uboot/patch/20221022092058.106052-1-heinrich.schuchardt@canonical.com/

>
> diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c
> index 4d08dd3763a..6ce0fcc168d 100644
> --- a/lib/efi_loader/efi_console.c
> +++ b/lib/efi_loader/efi_console.c
> @@ -461,10 +461,16 @@ static efi_status_t EFIAPI efi_cout_set_attribute(
>  }
>
>  /**
> - * efi_cout_clear_screen() - clear screen
> + * efi_clear_screen() - clear screen
>   */
>  static void efi_clear_screen(void)
>  {
> +       unsigned int row;
> +
> +       /* Avoid overwriting previous outputs on streaming consoles */
> +       for (row = 1; row < efi_cout_modes[efi_con_mode.mode].rows; row++)
> +               printf("\n");
> +
>         /*
>          * The Linux console wants both a clear and a home command. The video
>          * uclass does not support <ESC>[H without coordinates, yet.
> --
> 2.35.3
>

Regards,
SImon