Harvard Addressing

[Jim Blandy]

Matt Kern <matt.kern@undue.org> writes:
> As I mentioned in a previous email, I am in the process of porting GDB
> to a Harvard machine.  GDB requires us to flatten our two address spaces
> into a single, unified address space;  the code address space spans 0x0
> - 0x00ffffff, while the data address space spans 0x01000000 -
> 0x0100ffff.
>
> Currently, however the toolchain does not merge the address spaces;  the
> code address space spans 0x0 - 0x00ffffff, while the data address space
> spans 0x0 - 0x0000ffff.  This means that you can have a code symbol,
> foo, _and_ a data symbol, bar, both with VMA 0x2c0.

Is the toolchain yours to change?  If so, I'd really recommend
using the unified address space from the linker on down.  We've used
the unified address space approach for many architectures with
distinct address spaces, so this is well-explored territory.

> Alternatively, should I back out these changes and look to mod the
> toolchain to produce data addresses in the 0x01000000 - 0x0100ffff
> range?

(This is what I recommend.)