diff options
| author | Jan Kiszka <jan.kiszka@siemens.com> | 2023-01-18 22:24:59 +0100 |
|---|---|---|
| committer | Heinrich Schuchardt <heinrich.schuchardt@canonical.com> | 2023-01-20 16:38:52 +0100 |
| commit | e585b79ee4b1424f43dc7dbf66fc4f054255cb57 (patch) | |
| tree | 52b9af31a40e52fb829777340acdf36fc5dc3f30 /lib/efi_loader/efi_console.c | |
| parent | de94f0f3209e27ff36b264c58d5e6a8d54e07c65 (diff) | |
efi_loader: Avoid overwriting previous outputs on console screen clearing
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. Still, there
were remaining concerns about side effects, so this is provided as an
opt-in feature.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Diffstat (limited to 'lib/efi_loader/efi_console.c')
| -rw-r--r-- | lib/efi_loader/efi_console.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c index 9316995073e..1ed8c7aa36e 100644 --- a/lib/efi_loader/efi_console.c +++ b/lib/efi_loader/efi_console.c @@ -461,10 +461,21 @@ 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) { + if (CONFIG_IS_ENABLED(EFI_SCROLL_ON_CLEAR_SCREEN)) { + unsigned int row, screen_rows, screen_columns; + + /* Avoid overwriting previous outputs on streaming consoles */ + screen_rows = efi_cout_modes[efi_con_mode.mode].rows; + screen_columns = efi_cout_modes[efi_con_mode.mode].columns; + printf(ESC "[%u;%uH", screen_rows, screen_columns); + for (row = 1; row < screen_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. |