[PATCH] Make vm86 support optional

This adds an option to remove vm86 support under CONFIG_EMBEDDED.  Saves
about 5k.

This version eliminates most of the #ifdefs of the previous version and
instead uses function stubs in vm86.h.  Also, release_vm86_irqs is moved
from asm-i386/irq.h to a more appropriate home in vm86.h so that the stubs
can live together.

$ size vmlinux-baseline vmlinux-novm86
   text    data     bss     dec     hex filename
2920821  523232  190652 3634705  377611 vmlinux-baseline
2916268  523100  190492 3629860  376324 vmlinux-novm86

Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

7 files changed, 37 insertions, 3 deletions

diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index 4f40589e179c..be1880bb75b4 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -4,7 +4,7 @@
 
 extra-y := head.o init_task.o vmlinux.lds
 
-obj-y   := process.o semaphore.o signal.o entry.o traps.o irq.o vm86.o \
+obj-y   := process.o semaphore.o signal.o entry.o traps.o irq.o \
                 ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_i386.o \
                 pci-dma.o i386_ksyms.o i387.o dmi_scan.o bootflag.o \
                 quirks.o i8237.o
@@ -34,6 +34,7 @@ obj-$(CONFIG_ACPI_SRAT) 	+= srat.o
 obj-$(CONFIG_HPET_TIMER)        += time_hpet.o
 obj-$(CONFIG_EFI)               += efi.o efi_stub.o
 obj-$(CONFIG_DOUBLEFAULT)       += doublefault.o
+obj-$(CONFIG_VM86)              += vm86.o
 obj-$(CONFIG_EARLY_PRINTK)      += early_printk.o
 
 EXTRA_AFLAGS   := -traditional
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 607c06007508..4d704724b2f5 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -323,6 +323,7 @@ work_notifysig:				# deal with pending signals and
 
         ALIGN
 work_notifysig_v86:
+#ifdef CONFIG_VM86
         pushl %ecx                      # save ti_flags for do_notify_resume
         call save_v86_state             # %eax contains pt_regs pointer
         popl %ecx
@@ -330,6 +331,7 @@ work_notifysig_v86:
         xorl %edx, %edx
         call do_notify_resume
         jmp resume_userspace
+#endif
 
         # perform syscall exit tracing
         ALIGN
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 45e7f0ac4b04..035928f3f6c1 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -48,6 +48,7 @@
 #include <asm/processor.h>
 #include <asm/i387.h>
 #include <asm/desc.h>
+#include <asm/vm86.h>
 #ifdef CONFIG_MATH_EMULATION
 #include <asm/math_emu.h>
 #endif
diff --git a/include/asm-i386/irq.h b/include/asm-i386/irq.h
index 270f1986b19f..5169d7af456f 100644
--- a/include/asm-i386/irq.h
+++ b/include/asm-i386/irq.h
@@ -21,8 +21,6 @@ static __inline__ int irq_canonicalize(int irq)
         return ((irq == 2) ? 9 : irq);
 }
 
-extern void release_vm86_irqs(struct task_struct *);
-
 #ifdef CONFIG_X86_LOCAL_APIC
 # define ARCH_HAS_NMI_WATCHDOG          /* See include/linux/nmi.h */
 #endif
diff --git a/include/asm-i386/vm86.h b/include/asm-i386/vm86.h
index 40ec82c6914d..952fd6957380 100644
--- a/include/asm-i386/vm86.h
+++ b/include/asm-i386/vm86.h
@@ -16,7 +16,11 @@
 #define IF_MASK         0x00000200
 #define IOPL_MASK       0x00003000
 #define NT_MASK         0x00004000
+#ifdef CONFIG_VM86
 #define VM_MASK         0x00020000
+#else
+#define VM_MASK         0 /* ignored */
+#endif
 #define AC_MASK         0x00040000
 #define VIF_MASK        0x00080000      /* virtual interrupt flag */
 #define VIP_MASK        0x00100000      /* virtual interrupt pending */
@@ -200,9 +204,25 @@ struct kernel_vm86_struct {
  */
 };
 
+#ifdef CONFIG_VM86
+
 void handle_vm86_fault(struct kernel_vm86_regs *, long);
 int handle_vm86_trap(struct kernel_vm86_regs *, long, int);
 
+struct task_struct;
+void release_vm86_irqs(struct task_struct *);
+
+#else
+
+#define handle_vm86_fault(a, b)
+#define release_vm86_irqs(a)
+
+static inline int handle_vm86_trap(struct kernel_vm86_regs *a, long b, int c) {
+        return 0;
+}
+
+#endif /* CONFIG_VM86 */
+
 #endif /* __KERNEL__ */
 
 #endif
diff --git a/init/Kconfig b/init/Kconfig
index 9ac522a40130..f8f6929d8f25 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -237,6 +237,16 @@ config UID16
         help
           This enables the legacy 16-bit UID syscall wrappers.
 
+config VM86
+        depends X86
+        default y
+        bool "Enable VM86 support" if EMBEDDED
+        help
+          This option is required by programs like DOSEMU to run 16-bit legacy
+          code on X86 processors. It also may be needed by software like
+          XFree86 to initialize some video cards via BIOS. Disabling this
+          option saves about 6k.
+
 config CC_OPTIMIZE_FOR_SIZE
         bool "Optimize for size (Look out for broken compilers!)"
         default y
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 72cafc922d39..bd3b9bfcfcec 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -102,6 +102,8 @@ cond_syscall(sys_setresgid16);
 cond_syscall(sys_setresuid16);
 cond_syscall(sys_setreuid16);
 cond_syscall(sys_setuid16);
+cond_syscall(sys_vm86old);
+cond_syscall(sys_vm86);
 
 /* arch-specific weak syscall entries */
 cond_syscall(sys_pciconfig_read);