[2.6 patch] i386: always use 4k stacks

[Adrian Bunk <bunk@stusta.de>]

It seems most problems with 4k stacks are already resolved at least
in -mm.

I'd like to see this patch to always use 4k stacks in -mm now for 
finding any remaining problems before submitting this patch for 2.6.16.


Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Arjan van de Ven <arjan@infradead.org>

---

This patch was already sent on:
- 23 Nov 2005
- 14 Nov 2005

 arch/i386/Kconfig.debug        |   10 ----------
 arch/i386/kernel/irq.c         |   10 ----------
 include/asm-i386/irq.h         |   11 +++--------
 include/asm-i386/module.h      |    8 +-------
 include/asm-i386/thread_info.h |    6 +-----
 5 files changed, 5 insertions(+), 40 deletions(-)

--- linux-2.6.14-mm2-full/arch/i386/Kconfig.debug.old	2005-11-14 01:30:54.000000000 +0100
+++ linux-2.6.14-mm2-full/arch/i386/Kconfig.debug	2005-11-14 01:31:06.000000000 +0100
@@ -52,16 +52,6 @@
 	  portion of the kernel code won't be covered by a 2MB TLB anymore.
 	  If in doubt, say "N".
 
-config 4KSTACKS
-	bool "Use 4Kb for kernel stacks instead of 8Kb"
-	depends on DEBUG_KERNEL
-	help
-	  If you say Y here the kernel will use a 4Kb stacksize for the
-	  kernel stack attached to each process/thread. This facilitates
-	  running more threads on a system and also reduces the pressure
-	  on the VM subsystem for higher order allocations. This option
-	  will also use IRQ stacks to compensate for the reduced stackspace.
-
 config X86_FIND_SMP_CONFIG
 	bool
 	depends on X86_LOCAL_APIC || X86_VOYAGER
--- linux-2.6.14-mm2-full/include/asm-i386/irq.h.old	2005-11-14 01:31:18.000000000 +0100
+++ linux-2.6.14-mm2-full/include/asm-i386/irq.h	2005-11-14 01:31:29.000000000 +0100
@@ -27,14 +27,9 @@
 # define ARCH_HAS_NMI_WATCHDOG		/* See include/linux/nmi.h */
 #endif
 
-#ifdef CONFIG_4KSTACKS
-  extern void irq_ctx_init(int cpu);
-  extern void irq_ctx_exit(int cpu);
-# define __ARCH_HAS_DO_SOFTIRQ
-#else
-# define irq_ctx_init(cpu) do { } while (0)
-# define irq_ctx_exit(cpu) do { } while (0)
-#endif
+extern void irq_ctx_init(int cpu);
+extern void irq_ctx_exit(int cpu);
+#define __ARCH_HAS_DO_SOFTIRQ
 
 #ifdef CONFIG_IRQBALANCE
 extern int irqbalance_disable(char *str);
--- linux-2.6.14-mm2-full/include/asm-i386/thread_info.h.old	2005-11-14 01:31:45.000000000 +0100
+++ linux-2.6.14-mm2-full/include/asm-i386/thread_info.h	2005-11-14 01:32:11.000000000 +0100
@@ -53,11 +53,7 @@
 #endif
 
 #define PREEMPT_ACTIVE		0x10000000
-#ifdef CONFIG_4KSTACKS
-#define THREAD_SIZE            (4096)
-#else
-#define THREAD_SIZE		(8192)
-#endif
+#define THREAD_SIZE		(4096)
 
 #define STACK_WARN             (THREAD_SIZE/8)
 /*
--- linux-2.6.14-mm2-full/include/asm-i386/module.h.old	2005-11-14 01:32:18.000000000 +0100
+++ linux-2.6.14-mm2-full/include/asm-i386/module.h	2005-11-14 01:32:42.000000000 +0100
@@ -64,12 +64,6 @@
 #define MODULE_REGPARM ""
 #endif
 
-#ifdef CONFIG_4KSTACKS
-#define MODULE_STACKSIZE "4KSTACKS "
-#else
-#define MODULE_STACKSIZE ""
-#endif
-
-#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY MODULE_REGPARM MODULE_STACKSIZE
+#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY MODULE_REGPARM
 
 #endif /* _ASM_I386_MODULE_H */
--- linux-2.6.14-mm2-full/arch/i386/kernel/irq.c.old	2005-11-14 01:32:56.000000000 +0100
+++ linux-2.6.14-mm2-full/arch/i386/kernel/irq.c	2005-11-14 01:33:28.000000000 +0100
@@ -33,7 +33,6 @@
 }
 #endif
 
-#ifdef CONFIG_4KSTACKS
 /*
  * per-CPU IRQ handling contexts (thread information and stack)
  */
@@ -44,7 +43,6 @@
 
 static union irq_ctx *hardirq_ctx[NR_CPUS];
 static union irq_ctx *softirq_ctx[NR_CPUS];
-#endif
 
 /*
  * do_IRQ handles all normal device IRQ's (the special
@@ -58,10 +56,8 @@
 #ifdef CONFIG_DEBUG_PREEMPT
 	u32 count = preempt_count() & PREEMPT_MASK;
 #endif
-#ifdef CONFIG_4KSTACKS
 	union irq_ctx *curctx, *irqctx;
 	u32 *isp;
-#endif
 
 	irq_enter();
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
@@ -79,8 +75,6 @@
 	}
 #endif
 
-#ifdef CONFIG_4KSTACKS
-
 	curctx = (union irq_ctx *) current_thread_info();
 	irqctx = hardirq_ctx[smp_processor_id()];
 
@@ -118,7 +112,6 @@
 		irqctx->tinfo.preempt_count -= count;
 #endif
 	} else
-#endif
 		__do_IRQ(irq, regs);
 
 	irq_exit();
@@ -128,8 +121,6 @@
 	return 1;
 }
 
-#ifdef CONFIG_4KSTACKS
-
 /*
  * These should really be __section__(".bss.page_aligned") as well, but
  * gcc's 3.0 and earlier don't handle that correctly.
@@ -228,7 +219,6 @@
 }
 
 EXPORT_SYMBOL(do_softirq);
-#endif
 
 /*
  * Interrupt statistics: