[LinuxBIOS] [PATCH] v3: fix absolute calls from initram

Corey Osgood corey.osgood at gmail.com
Tue Dec 4 05:16:37 CET 2007

Carl-Daniel Hailfinger wrote:
> 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.

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.

> Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

I've attached a QEMU bootlog, it seems to make the calls to the right
places, but still won't boot FILO. Per IRC, I won't ack at the moment
until more people can test, but it does look good to me :)

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