I have hit an issue with long calls on arm gcc (version 3.0.4 with the
long-calls patch). I see someone else reported this issue on 30 April,
has there been a resolution?
The issue is as follows:
void FnHi() __attribute__((section("high"))) __attribute__((long_call));
void FnLo() __attribute__((section("low"))) __attribute__((long_call));
I can call FnHi() from anywhere within the "low" section, however I
cannot call FnLo() from the "high" section because the _call_via_rX
stub is located in "low", and hence the call to _call_via_rX gets
truncated by the linker.
Is there a way to get gcc to generate the stubs in all sections?
As things stand at the moment: "no".
Even if you could, it would not work, because the linker would just
complain about duplicate definitions of the _call_via_rX symbols. What
you would need is for gcc to generate branches to functions called
_call_via_rX_from_section_<foo> and then have it generate weak
versions of these functions in every compiled source file that uses
them.
You might be able to achieve a similar effect through judicious use of
partial linking and special linker scrips. ie you could perform a
partial link of the "high" section code with libgcc.a to resolve all
of the references to __call_via_rX there. (Making sure that the
script used places the object file containing the _call_via_rX symbols
close to the "high" section). You could then do a similar partial
link for the "low" section. The strip out any remaining occurrences of
the _call_via_rX symbols and perform a final link. It *might* work....