dead hvc_console with kdump kernel

[Michael Ellerman]

On Wed, 8 Mar 2006 22:45, Olaf Hering wrote:
>  On Wed, Mar 08, Michael Ellerman wrote:
> > So we take an interrupt, and while we're processing it we decide we
> > should panic, this happens for example if we panic via sysrq.
>
> You are right, sleep 2 ; echo c > /proc/sysrq-trigger ; sleep 2 gives me
> a working console.

Yep, and with this patch, my veth (irq 185) is dead in the second kernel.

Index: kdump/arch/powerpc/kernel/irq.c
===================================================================
--- kdump.orig/arch/powerpc/kernel/irq.c        2006-03-07 10:00:41.000000000 +1100
+++ kdump/arch/powerpc/kernel/irq.c     2006-03-08 17:22:44.000000000 +1100
@@ -40,6 +40,7 @@
 #include <linux/timex.h>
 #include <linux/config.h>
 #include <linux/init.h>
+#include <linux/debugfs.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
@@ -181,6 +182,16 @@ void fixup_irqs(cpumask_t map)
 }
 #endif

+static u32 dodgy_hack_should_crash = 0;
+
+void dodgy_hack_init(void)
+{
+       debugfs_create_bool("dodgy_hack_should_crash",
+                       S_IFREG | S_IRWXUGO | ~S_IXUGO,
+                       NULL, &dodgy_hack_should_crash);
+}
+__initcall(dodgy_hack_init);
+
 void do_IRQ(struct pt_regs *regs)
 {
        int irq;
@@ -214,6 +225,11 @@ void do_IRQ(struct pt_regs *regs)
         */
        irq = ppc_md.get_irq(regs);

+       if (dodgy_hack_should_crash && irq == 185) {
+               printk("do_IRQ: got irq %d, crashing.\n", irq);
+               crash_kexec(regs);
+       }
+
        if (irq >= 0) {
 #ifdef CONFIG_IRQSTACKS
                /* Switch to the irq stack to handle this */