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-rw-r--r--arch/x86/boot/main.c24
1 files changed, 18 insertions, 6 deletions
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index 22ca62b..7828da5 100644
--- a/arch/x86/boot/main.c
+++ b/arch/x86/boot/main.c
@@ -100,20 +100,32 @@ static void set_bios_mode(void)
#endif
}
-void main(void)
+static void init_heap(void)
{
- /* First, copy the boot header into the "zeropage" */
- copy_boot_params();
+ char *stack_end;
- /* End of heap check */
if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
- heap_end = (char *)(boot_params.hdr.heap_end_ptr
- +0x200-STACK_SIZE);
+ asm("leal %P1(%%esp),%0"
+ : "=r" (stack_end) : "i" (-STACK_SIZE));
+
+ heap_end = (char *)
+ ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
+ if (heap_end > stack_end)
+ heap_end = stack_end;
} else {
/* Boot protocol 2.00 only, no heap available */
puts("WARNING: Ancient bootloader, some functionality "
"may be limited!\n");
}
+}
+
+void main(void)
+{
+ /* First, copy the boot header into the "zeropage" */
+ copy_boot_params();
+
+ /* End of heap check */
+ init_heap();
/* Make sure we have all the proper CPU support */
if (validate_cpu()) {
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