arch-specific funcs in libgloss to override libnosys

[Mike Frysinger <vapier at gentoo dot org>]

i'm not terribly familiar with libgloss' source layout.  ive reviewed the
porting doc, but it seems some pieces are out of date, and it doesnt exactly
explain how one folds a bsp lib from libgloss into gcc's default linker
output.

in my case, i'm looking at overriding the default _exit() symbol.  the
libnosys code attempts to trigger a divide-by-zero exception which doesnt
exist on Blackfin parts.  atm, our local tree is doing:
libgloss/libnosys/_exit.c:
#ifdef __BFIN__
  asm ("EXCPT 0;");
#else
  /* Default stub just causes a divide by 0 exception.  */
  int x = rc / INT_MAX;
  x = 4 / x;
  asm volatile ("" : : "r" (x));
#endif
clearly this goes against the whole point of libnosys :)

there is also an additional support function i need to add that is Blackfin-
specific and required by gcc (for clearing caches).

so what i'm thinking is that i declare a new libbsp.a in bfin/Makefile.in,
stick a _exit.c file in there as well as the Blackfin-specific files, and then
build them up as part of libgloss.

then i modify the Blackfin elf gcc spec like so:
-#define LIB_SPEC "--start-group -lc %{msim:-lsim}%{!msim:-lnosys} --end-group \
+#define LIB_SPEC "--start-group -lc %{msim:-lsim}%{!msim:-lbsp -lnosys} --end-group \

is this the way to go ?  or am i completely off base ?
-mike

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