Displaying 2 results from an estimated 2 matches for "efi_write_char".
2025 Apr 21
0
[PATCH] Improve EFI console logging
...on Debian [0], I came across an issue where
error messages generated early in the syslinux boot process through
writestr() didn't end up appearing on-screen. Instead, it appeared
that only the cursor moved.
I discovered that it's because the early code passes a video attribute
of 0 to the efi_write_char() function, which is black-on-black, and
produces invisible output.
The output can actually be read on the serial line. For example, if we
have a serial line dump in the file serial.dump, and we have problems
with loading ldlinux.e32, the following can be used to read the message:
$ ansi2txt...
2025 Apr 22
0
[PATCH] Improve EFI console logging
...error messages generated early in the syslinux boot process through
>> writestr() didn't end up appearing on-screen. Instead, it appeared
>> that only the cursor moved.
>>
>> I discovered that it's because the early code passes a video attribute
>> of 0 to the efi_write_char() function, which is black-on-black, and
>> produces invisible output.
>>
>> The output can actually be read on the serial line. For example, if we
>> have a serial line dump in the file serial.dump, and we have problems
>> with loading ldlinux.e32, the following can...