Re: Controlling allocation in 64-bit space

[Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>]

Davyd Madeley <davyd@fugro-fsi.com.au> writes:

> We're looking to do what would be called 'a dodgy hack'.
>
> We have some Fortran code that puts arrays of size 1 into the .text section of a
> binary, These arrays will have 64-bit addresses. We then want to allocate a
> section of memory using a C function that returns an offset from our array
> address as a 4-byte uint (Fortran 77 has no pointers). We can then access
> ARRAY(offset + 54) which equates to &ARRAY + offset + 54 bytes. In effect it is
> a giant buffer overrun, but this is apparently the established way to do memory
> allocation in Fortran.
>
> The ultimate solution will be to #define a POINTER type that is the correct size
> for the architecture, unfortunately there is an awful lot of code to fix.
>
> What we want to do is be able to allocate a region of memory that has an offset
> that is within 4-bytes of &ARRAY, but this goes beyond my knowledge of the
> allocator, that I'm not even sure where to start looking.
>
> Any help would be much appreciated.
>
> Regards,
> --davyd
>
> PS. please CC replies, am off list

mmap /dev/zero, that way you can pick the address you want.

MfG
        Goswin