switch-coreboot/arch
Carl-Daniel Hailfinger aa9bb6e81b Absolute calls from initram were only working from the file which had
_MAINOBJECT #defined. Calls from all other files ended up in nirvana
because the compiler was not able to calculate the address of the
wrapper for the absolute call. The linker tried, but failed miserably.
Use the -combine flag and compile all of initram at once. This enables
GCC to calculate the address of the abscall wrapper, resulting in
working code.

Segher Boessenkool thinks the patched code works only by accident
because GCC has no way to specify generation of XIP code. According to
him, future GCC versions or other circumstances may break the code.

While this patch makes code work for now, it does NOT check whether the
generated code tries to write to memory outside the stack (general
writable data). That will of course fail, but I hope porters are smart
enough to avoid that.

Corey Osgood writes:
Great work tracking this down! This is okay for now, but we need to look
for a better solution in the future. Counting on porters who may or may
not remember this discussion to avoid something isn't good
future-proofing.

Checking the ELF sections for read-write data and stopping the build
with an error could make this future-proof.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Corey Osgood <corey.osgood@gmail.com>


git-svn-id: svn://coreboot.org/repository/LinuxBIOSv3@537 f3766cd6-281f-0410-b1cd-43a5c92072e9
2007-12-04 22:42:38 +00:00
..
x86 Absolute calls from initram were only working from the file which had 2007-12-04 22:42:38 +00:00