[syslinux] EFI: HP + syslinux = crash

[Oscar Roozen]

On 05-08-15 15:28, Gene Cumm wrote:
>>> 0x2f8 is a BIOSism.
>
>> Is this a problem? The example in the comments said 0x3f8 which is COM1.
>
> It means that a BIOS IO port for a UART won't work for EFI.  No value
> for DEBUG_PORT will do anything unless someone's got some translation
> "glue" to take the attempts to open the UART and use an EFI handle
> instead.


That's weird, since enabling this finally got me some debugging output 
from dprintf(). I think I'm being lucky here! HP apparently provides the 
necessary glue.

What would be the correct way to enable debugging under EFI? Normal 
printf output remains invisible, so DEBUG_STDIO doesn't work.

If there is nothing yet, I think a wrapper around printf (and *prinf) is 
needed. This should [v]sprintf() to a buffer and then print the 
resulting buffer using APrint("%a", buffer) if EFI_BUILD is defined.