[PATCH] Eat keys on panic

[PATCH] Eat keys on panic

[Andi Kleen]

[forgot to cc linux-kernel with the other mail]

I have a weird KVM that refuses to switch consoles when the keyboard
controller doesn't process key presses. Actually it switches, but only
after a long delay which usually drives me crazy.

This patch changes the panic loop to eat keys from the keyboard controller
on i386 boxes. With that I can switch consoles after a panic.

The ioport should be available on all PC like boxes, the reset code also
depends on it being at a fixed place.

ioport.c is not the best place in the world to place the function,
but I didn't find a better one. It cannot be inlined to avoid include
hell.

-Andi

Index: linux/arch/i386/kernel/ioport.c
===================================================================
RCS file: /home/cvs/linux-2.5/arch/i386/kernel/ioport.c,v
retrieving revision 1.17
diff -u -u -r1.17 ioport.c
--- linux/arch/i386/kernel/ioport.c	30 May 2003 20:12:29 -0000	1.17
+++ linux/arch/i386/kernel/ioport.c	31 May 2003 10:24:18 -0000
@@ -15,6 +15,7 @@
 #include <linux/stddef.h>
 #include <linux/slab.h>
 #include <linux/thread_info.h>
+#include <asm/io.h>
 
 /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
 static void set_bitmap(unsigned long *bitmap, short base, short extent, int new_value)
@@ -128,4 +129,10 @@
 	/* Make sure we return the long way (not sysenter) */
 	set_thread_flag(TIF_IRET);
 	return 0;
+}
+
+void eat_key(void)
+{
+        if (inb(0x60) & 1) 
+                inb(0x64);
 }
Index: linux/include/asm-i386/system.h
===================================================================
RCS file: /home/cvs/linux-2.5/include/asm-i386/system.h,v
retrieving revision 1.37
diff -u -u -r1.37 system.h
--- linux/include/asm-i386/system.h	30 May 2003 20:10:39 -0000	1.37
+++ linux/include/asm-i386/system.h	31 May 2003 10:24:24 -0000
@@ -476,4 +476,7 @@
 #define BROKEN_PNP_BIOS		0x0004
 #define BROKEN_CPUFREQ		0x0008
 
+#define HAVE_EAT_KEY
+void eat_key(void);
+
 #endif
Index: linux/kernel/panic.c
===================================================================
RCS file: /home/cvs/linux-2.5/kernel/panic.c,v
retrieving revision 1.20
diff -u -u -r1.20 panic.c
--- linux/kernel/panic.c	30 May 2003 20:14:20 -0000	1.20
+++ linux/kernel/panic.c	31 May 2003 10:24:26 -0000
@@ -96,8 +96,11 @@
         disabled_wait(caller);
 #endif
 	local_irq_enable();
-	for (;;)
-		;
+	for (;;) { 
+#ifdef HAVE_EAT_KEY
+		eat_key();
+#endif
+	} 
 }
 
 /**

Re: [PATCH] Eat keys on panic

[Alan Cox]

On Sad, 2003-05-31 at 12:56, Andi Kleen wrote:

> +void eat_key(void)
> +{
> +        if (inb(0x60) & 1) 
> +                inb(0x64);
>  }

This will crash at least one of my machines. The keyboard controller
has mandatory access delays of up to 1mS. Respect them or some stuff
dies horribly.

Re: [PATCH] Eat keys on panic

[Andi Kleen]

On Sat, May 31, 2003 at 03:14:51PM +0100, Alan Cox wrote:
> On Sad, 2003-05-31 at 12:56, Andi Kleen wrote:
> 
> > +void eat_key(void)
> > +{
> > +        if (inb(0x60) & 1) 
> > +                inb(0x64);
> >  }
> 
> This will crash at least one of my machines. The keyboard controller
> has mandatory access delays of up to 1mS. Respect them or some stuff
> dies horribly.

1ms? Is it clocked in Khz or something? 

Here is a new version that is hopefully Alan's-broken-chipset proof.
I also added the request comment.

-Andi

P.S.: This is different from the panic blink code. The two can easily
coexist though.


Index: linux/arch/i386/kernel/ioport.c
===================================================================
RCS file: /home/cvs/linux-2.5/arch/i386/kernel/ioport.c,v
retrieving revision 1.17
diff -u -u -r1.17 ioport.c
--- linux/arch/i386/kernel/ioport.c	30 May 2003 20:12:29 -0000	1.17
+++ linux/arch/i386/kernel/ioport.c	31 May 2003 14:24:16 -0000
@@ -15,6 +15,8 @@
 #include <linux/stddef.h>
 #include <linux/slab.h>
 #include <linux/thread_info.h>
+#include <asm/io.h>
+#include <linux/delay.h>
 
 /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
 static void set_bitmap(unsigned long *bitmap, short base, short extent, int new_value)
@@ -128,4 +130,14 @@
 	/* Make sure we return the long way (not sysenter) */
 	set_thread_flag(TIF_IRET);
 	return 0;
+}
+
+/* Some KVMs don't switch consoles unless the keyboard is served. */
+void eat_key(void)
+{
+	if (inb(0x60) & 1) {
+		mdelay(1);
+		inb(0x64);
+	}
+	mdelay(1);
 }
Index: linux/include/asm-i386/system.h
===================================================================
RCS file: /home/cvs/linux-2.5/include/asm-i386/system.h,v
retrieving revision 1.37
diff -u -u -r1.37 system.h
--- linux/include/asm-i386/system.h	30 May 2003 20:10:39 -0000	1.37
+++ linux/include/asm-i386/system.h	31 May 2003 14:24:22 -0000
@@ -476,4 +476,7 @@
 #define BROKEN_PNP_BIOS		0x0004
 #define BROKEN_CPUFREQ		0x0008
 
+#define HAVE_EAT_KEY
+void eat_key(void);
+
 #endif
Index: linux/kernel/panic.c
===================================================================
RCS file: /home/cvs/linux-2.5/kernel/panic.c,v
retrieving revision 1.20
diff -u -u -r1.20 panic.c
--- linux/kernel/panic.c	30 May 2003 20:14:20 -0000	1.20
+++ linux/kernel/panic.c	31 May 2003 14:24:24 -0000
@@ -96,8 +96,11 @@
         disabled_wait(caller);
 #endif
 	local_irq_enable();
-	for (;;)
-		;
+	for (;;) { 
+#ifdef HAVE_EAT_KEY
+		eat_key();
+#endif
+	} 
 }
 
 /**

> 
> 

Re: [PATCH] Eat keys on panic

[Adrian Bunk]

On Sat, May 31, 2003 at 05:45:21PM +0200, Andi Kleen wrote:
>...
> --- linux/arch/i386/kernel/ioport.c	30 May 2003 20:12:29 -0000	1.17
> +++ linux/arch/i386/kernel/ioport.c	31 May 2003 14:24:16 -0000
> @@ -15,6 +15,8 @@
>  #include <linux/stddef.h>
>  #include <linux/slab.h>
>  #include <linux/thread_info.h>
> +#include <asm/io.h>
> +#include <linux/delay.h>
>...

Could you move the #include <linux/delay.h> above the
#include <asm/io.h> ?

TIA
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed