On 15.10.24 12:19, Mark Kettenis wrote:
Date: Mon, 14 Oct 2024 15:11:50 -0600
From: Tom Rini <tr...@konsulko.com>
On Mon, Oct 14, 2024 at 01:13:41PM -0600, Simon Glass wrote:
[snip]
Or perhaps just have a way to turn it off? I first sent this patch
last November. It is just wrong to generate output like this which we
don't want. There isn't even a test for it, so just add a way to
disable it, and be done!
I don't know that it's unwanted. As I'm trying to get Heinrich to
explain, _why_ does efi_setup_console_size need to exist, and do what it
does? This isn't the case of color-coding the output of tests as they
happen, there must be a reason we care about knowing the console size.
At that point we can figure out if the right answer is:
- Don't generate that check on serial ports, it's somewhere between
misleading to wrong.
- text-based tests just need to expect and skip it because there's a
good reason to need to know the console size and not just assume
80x24.
- Something else we won't know until it's clearly explained why we do
this.
Sadly this is a misfeature of UEFI. The EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
is required if console devices are supported by the UEFI
implementation, and is built around the concept of "text mode" with a
fixed number of character rows and columns. That pretty much assumes
there is some sort of terminal emulator on the other end. And this is
pretty much incompatible with anything that just want to log serial
output.
I think it is possible to do better though. Instead of calling
efi_setup_console_size() in efi_init_obj_list(), we could postpone
this until the application makes a call that requires us to know the
size. This would mean that a simple EFI application that just uses
EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.OutputString() (such as the Hello
world EFI application or the OpenBSD EFI bootloader) wouldn't have to
do the size query.
The implementation of EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.OutputString()
needs to know the output size to update the cursor position in
EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.MODE.CursorColumn
EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.MODE.CursorRow
The EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL is passed to the entry point of any
EFI application via the system table.
We could delay the invocation of efi_setup_console_size() to the launch
of the first EFI application (efi_start_image()).
Best regards
Heinrich
