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-rw-r--r--i386/i386at/model_dep.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/i386/i386at/model_dep.c b/i386/i386at/model_dep.c
index 1546077..9f0a1c7 100644
--- a/i386/i386at/model_dep.c
+++ b/i386/i386at/model_dep.c
@@ -196,11 +196,18 @@ void db_reset_cpu()
void
mem_size_init()
{
+ vm_size_t phys_last_kb;
+
/* Physical memory on all PCs starts at physical address 0.
XX make it a constant. */
phys_first_addr = 0;
- phys_last_addr = 0x100000 + (boot_info.mem_upper * 0x400);
+ phys_last_kb = 0x400 + boot_info.mem_upper;
+ /* Avoid 4GiB overflow. */
+ if (phys_last_kb < 0x400 || phys_last_kb >= 0x400000)
+ phys_last_kb = 0x400000 - 1;
+
+ phys_last_addr = phys_last_kb * 0x400;
avail_remaining
= phys_last_addr - (0x100000 - (boot_info.mem_lower * 0x400)
- 0x1000);