Changeset 92b67b18 in rtems for c/src/lib/libbsp/powerpc/shared

2003-09-26 Till Strauman <strauman@…>

PR 496/bsps

• startup/sbrk.c: New file.
• startup/bspstart.c: This patch implements 'sbrk' for the powerpc-shared BSP to work around what's known as the '32Mb problem' in combination with run-time loaded code. GCC normally generates (PowerPC) code doing 'short jumps' which requires all text segments being in the same 32Mb area of memory. However, some run-time loaders use (e.g. heap-) memory violating the stated limitation on hardware with more than 32Mb of memory. (NOTE: portable loaders are probably not even aware of this GCC/CPU specific problem.)

This patch implements a simple workaround: At boot time, the system is
only provided with 32Mb of memory. The user is supposed to load all
necessary modules prior to that limit being exhausted. Once that
happens, newlib/malloc end up trying to 'sbrk()' for more memory and
the implementation provided by this patch will then make the rest of
the physical memory available.