[PATCH] Make vm86 support optional

From: Matt Mackall
Date: Wed Dec 28 2005 - 15:29:55 EST


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@xxxxxxxxxxx>

Index: 2.6.15-misc/arch/i386/kernel/Makefile
===================================================================
--- 2.6.15-misc.orig/arch/i386/kernel/Makefile 2005-12-28 02:01:39.000000000 -0600
+++ 2.6.15-misc/arch/i386/kernel/Makefile 2005-12-28 02:02:02.000000000 -0600
@@ -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
@@ -36,6 +36,7 @@ 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
Index: 2.6.15-misc/init/Kconfig
===================================================================
--- 2.6.15-misc.orig/init/Kconfig 2005-12-28 02:01:39.000000000 -0600
+++ 2.6.15-misc/init/Kconfig 2005-12-28 02:02:02.000000000 -0600
@@ -342,6 +342,16 @@ 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"
default y if ARM || H8300
Index: 2.6.15-misc/kernel/sys_ni.c
===================================================================
--- 2.6.15-misc.orig/kernel/sys_ni.c 2005-12-28 02:01:39.000000000 -0600
+++ 2.6.15-misc/kernel/sys_ni.c 2005-12-28 02:02:02.000000000 -0600
@@ -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);
Index: 2.6.15-misc/arch/i386/kernel/process.c
===================================================================
--- 2.6.15-misc.orig/arch/i386/kernel/process.c 2005-12-28 02:01:39.000000000 -0600
+++ 2.6.15-misc/arch/i386/kernel/process.c 2005-12-28 02:02:02.000000000 -0600
@@ -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
Index: 2.6.15-misc/include/asm-i386/irq.h
===================================================================
--- 2.6.15-misc.orig/include/asm-i386/irq.h 2005-12-28 02:01:39.000000000 -0600
+++ 2.6.15-misc/include/asm-i386/irq.h 2005-12-28 02:02:02.000000000 -0600
@@ -21,8 +21,6 @@ static __inline__ int irq_canonicalize(i
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
Index: 2.6.15-misc/include/asm-i386/vm86.h
===================================================================
--- 2.6.15-misc.orig/include/asm-i386/vm86.h 2005-12-28 02:01:39.000000000 -0600
+++ 2.6.15-misc/include/asm-i386/vm86.h 2005-12-28 02:36:48.000000000 -0600
@@ -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
Index: 2.6.15-misc/arch/i386/kernel/entry.S
===================================================================
--- 2.6.15-misc.orig/arch/i386/kernel/entry.S 2005-12-28 01:48:00.000000000 -0600
+++ 2.6.15-misc/arch/i386/kernel/entry.S 2005-12-28 12:23:44.000000000 -0600
@@ -341,6 +341,7 @@ work_notifysig: # deal with pending s

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
@@ -348,6 +349,7 @@ work_notifysig_v86:
xorl %edx, %edx
call do_notify_resume
jmp resume_userspace
+#endif

# perform syscall exit tracing
ALIGN


--
Mathematics is the supreme nostalgia of our time.
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