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Re: Segment registers support for i386


Rémy Saissy writes:

 > > It would take a massive target-specific backend hack to make that
 > > happen, as GCC > currently only supports flat address spaces. ;-)
 > 
 > I don't understand why.
 > gcc currently consider every data access on i386 to be %ds:offset or %ss:offset
 > depending on the instruction.

No, that's not true.  gcc doesn't know about %ds or %ss.

 > The purpose is only to add a way to explicitly indicate the section
 > to use then is could be %gs:offset or %fs:offset.
 > 
 > I'm new in gcc hacking therefore I still have to learn more about the
 > internals but
 > at first glance it doesn't sounds like a so big work.

You'd have to teach gcc about different address spaces.  For example,
gcc would have to know that %gs:foo couldn't be accessed via %ds.

Andrew.


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