Re: gdb vs. gdbserver with -mips3 / 32bitmode userspace

[Daniel Jacobowitz <dan@debian.org>]

On Wed, Feb 01, 2006 at 09:26:57AM -0800, Michael Uhler wrote:
> Daniel,
> 
> The O/S maybe doing something different, but the architecture has 3 bits in
> Status: KX, SX, and UX that enable access to the address space above 32
> bits.  With these bits off, an attempt to access these addresses causes an
> exception.  So while 32-bit apps have the full 64-bit address space, most of
> it is inaccessible to the 32-bit app.

That's not actually what I was referring to: there's at least one MIPS
implementation where the results of 32-bit arithmetic operations are
not just architecturally unpredictable but actually wrong if the upper
bits are not properly sign extended (I might be misremembering, but I
think I'm talking about the SB-1).  That's the sort of thing that can
be basically impossible to track down if your debugger doesn't show
you the whole register.

-- 
Daniel Jacobowitz
CodeSourcery