m68k reloc types

[Andreas Schwab]

Roman Zippel <zippel@linux-m68k.org> writes:

> But why does i386 doesn't need the kludgy hack in R_386_GOTPC to setup the 
> pic register?

Sorry, I can't parse this sentence.

>> > That R_68K_GOT32O is the same as R_386_GOT32 is not a little confusing? 
>> 
>> No.  Why?
>
> I could live it, if it would be documented somewhere publicly.

Well, they are documented fully in the m68k processor supplement to the
SysV ABI.  You may be able to find a copy in some university library.

> Ok, m68k could simply use pc relative addressing to access local symbols, 
> but which reloc type should be used to void creating the plt/got entry?

As you already wrote, use pc-relative addressing with any PIC modifier.

> Should both create a got entry?

Sure.

> In what other situation can R_68K_GOT32 be used for?

When you want the pc-relative address of the GOT entry for a symbol.
Ususally only used for _GLOBAL_OFFSET_TABLE_, but can be used for any
other symbol as well (but gcc does not use this).

> E.g. R_386_GOTOFF never creates a got entry.

It is used to simulate the missing pc-relative addressing mode with
pic-register-relative addressing.  Thus it is only usable for symbols that
don't need a GOT entry.

> BTW what's the difference between R_68K_PLT32O and R_68K_PLT32? A small 
> code example would be useful here. The former isn't generated by binutils.

They are similar to the GOT counterparts, but address the PLT entry
instead of the GOT entry.  R_64K_PLT32 is used for function calls.  I've
never been able to figure out where R_68K_PLT32O is supposed to be used,
it's maybe only defined for completeness.

> This doesn't really explain, why a reloc type should behave differently 
> dependening on the symbol.

Well, such is life.  I didn't define the m68k ABI.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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