In article <200109170253.WAA03795@biohazard-cafe.mit.edu>,
Matthew Fredette <fredette@MIT.EDU> wrote:

Old sun binaries might have mapped page 0 to 0, so that *0 does not
core dump (remember the vax :-). This is just speculation.

christos

>
>Hi.  I'm testing out COMPAT_SUNOS for NetBSD/sun2, trying to run some
>68010 SunOS 3 binaries.  I've got a mix of NMAGIC and ZMAGIC.  The few
>NMAGIC ones I've tried work.  The ZMAGIC binaries I've tried usually
>get SEGV trying to access memory below the text start at 0x2000, an
>area that our emulation leaves unmapped.
>
>I've done some light disassembly of the binaries.  So far the access
>is always frame pointer relative with %fp holding zero.  Early on,
>crt0.s makes a point to load %fp with zero, so I'm thinking that isn't
>a coincidence and that there's supposed to be something below the text
>start.  Does anyone know if old SunOS mapped these low addresses
>anywhere?
>
>Thanks,
>
>Matt
>
>--
>Matt Fredette
>http://mit.edu/fredette/www