[PATCH] i386: Fix UP gdt bugs

Fixes two problems with the GDT when compiling for uniprocessor:
 - There's no percpu segment, so trying to load its selector into %fs fails.
   Use a null selector instead.
 - The real gdt needs to be loaded at some point.  Do it in cpu_init().

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index ced2da8a0d6..70f3515c3db 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -750,6 +750,7 @@ extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);
 
 extern void cpu_set_gdt(int);
+extern void switch_to_new_gdt(void);
 extern void cpu_init(void);
 
 extern int force_mwait;
diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h
index 07e70624d87..597a47c2515 100644
--- a/include/asm-i386/segment.h
+++ b/include/asm-i386/segment.h
@@ -75,7 +75,11 @@
 #define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8)
 
 #define GDT_ENTRY_PERCPU                        (GDT_ENTRY_KERNEL_BASE + 15)
+#ifdef CONFIG_SMP
 #define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8)
+#else
+#define __KERNEL_PERCPU 0
+#endif
 
 #define GDT_ENTRY_DOUBLEFAULT_TSS       31