[SeaBIOS] Re: recent ld built for x86_64 fails to accept 16bit code as input (seabios build)

[Kevin O'Connor]

On Sat, Jul 11, 2020 at 09:22:30AM +0300, Michael Tokarev wrote:
> 11.07.2020 03:08, Kevin O'Connor wrote:
> []
> > As for the particular workaround, "-z allowexec" generates a warning
> > on current versions of ld.  Given that, for SeaBIOS, my first reaction
> > would probably be to change the SeaBIOS build to unconditionally clear
> > the flag in the intermediate binary than to deploy a more complicated
> > ld version check to set the given command-line flag.  I'd like to give
> > that some more thought though.
> 
> Can't seabios use the way suggested by Andreas Schwab, namely .incbin
> assembler instruction?

SeaBIOS has some funky linking requirements.  It needs to link 16bit
code, 32bit "segmented" code, and normal 32bit code.  There's a
document online describing a bit of this at:
https://www.seabios.org/Linking_overview

The main limitation to simple ".incbin" usage is that SeaBIOS needs to
put a variety of 16bit sections along with 32bit "segmented" sections
at certain fixed memory locations.  So, there is no one simple .incbin
directive that would replace the final linking step.  It's certainly
possible to come up with an alternative linking mechanism (or to even
manually assemble the final image), but I suspect the alternatives
will come with further complexity.  Certainly something to look at
though.

Cheers,
-Kevin