Add stubdomain support. See stubdom/README for usage details.

- Move PAGE_SIZE and STACK_SIZE into __PAGE_SIZE and __STACK_SIZE in
  arch_limits.h so as to permit getting them from there without
  pulling all the internal Mini-OS defines.
- Setup a xen-elf cross-compilation environment in stubdom/cross-root
- Add a POSIX layer on top of Mini-OS by linking against the newlib C
  library and lwIP, and implementing the Unixish part in mini-os/lib/sys.c
- Cross-compile zlib and libpci too.
- Add an xs.h-compatible layer on top of Mini-OS' xenbus.
- Cross-compile libxc with an additional xc_minios.c and a few things
  disabled.
- Cross-compile ioemu with an additional block-vbd, but without sound,
  tpm and other details.  A few hacks are needed:
  - Align ide and scsi buffers at least on sector size to permit
  direct transmission to the block backend. While we are at it, just
  page-align it to possibly save a segment. Also, limit the scsi
  buffer size because of limitations of the block paravirtualization
  protocol.
  - Allocate big tables dynamically rather that letting them go to
  bss: when Mini-OS gets installed in memory, bss is not lazily
  allocated, and doing so during Mini-OS is unnecessarily trick while
  we can simply use malloc.
- Had to change the Mini-OS compilation somehow, so as to export
  Mini-OS compilation flags to the Makefiles of libxc and ioemu.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/extras/mini-os/mm.c b/extras/mini-os/mm.c
index 11e249d421..f204fa66ec 100644
--- a/extras/mini-os/mm.c
+++ b/extras/mini-os/mm.c
@@ -360,6 +360,29 @@ void free_pages(void *pointer, int order)
    
 }
 
+#ifdef HAVE_LIBC
+void *sbrk(ptrdiff_t increment)
+{
+    unsigned long old_brk = brk;
+    unsigned long new_brk = old_brk + increment;
+
+    if (new_brk > heap_end) {
+	printk("Heap exhausted: %p + %lx = %p > %p\n", old_brk, increment, new_brk, heap_end);
+	return NULL;
+    }
+    
+    if (new_brk > heap_mapped) {
+        unsigned long n = (new_brk - heap_mapped + PAGE_SIZE - 1) / PAGE_SIZE;
+        do_map_zero(heap_mapped, n);
+        heap_mapped += n * PAGE_SIZE;
+    }
+
+    brk = new_brk;
+
+    return (void *) old_brk;
+}
+#endif
+
 
 
 void init_mm(void)