[Xen-ia64-devel] [RFC][Patch] fix boot xen-ia64 on some ia64 platforms

[Akio Takebe]

Hi,

The following changeset broke booting xen-ia64 on some kinds of ia64 boxes.
http://xenbits.xensource.com/ext/ia64/xen-unstable.hg/rev/3fd8f9b34941

The tasklet_schedule call raise_softirq().
Because raise_softirq() use per_cpu, if we access per_cpu before cpu_init()
the behavior would be unexpected.

I make the following patch for this investigation.
It can boot xen-ia64 on the ia64 boxes.
I'm not sure why Tiger4 can boot the latest xen-ia64.
I didn't find a good-looking solution, what do you think about it?

diff -r 8c806c66a597 xen/arch/ia64/linux-xen/setup.c
--- a/xen/arch/ia64/linux-xen/setup.c   Tue Apr 14 14:04:58 2009 +0900
+++ b/xen/arch/ia64/linux-xen/setup.c   Tue Apr 21 12:03:44 2009 +0900
@@ -67,6 +67,7 @@
 #include <xen/kexec.h>
 #endif

+int enable_dom0_con_tasklet=0;
 #if defined(CONFIG_SMP) && (IA64_CPU_SIZE > PAGE_SIZE)
 # error "struct cpuinfo_ia64 too big!"
 #endif
@@ -592,6 +593,9 @@ late_setup_arch (char **cmdline_p)
 #endif

        cpu_init();     /* initialize the bootstrap CPU */
+
+       enable_dom0_con_tasklet=1;
+       printk("AAA: enable_dom0_con_tasklet\n");

 #ifdef CONFIG_ACPI_BOOT
        acpi_boot_init();
diff -r 8c806c66a597 xen/drivers/char/console.c
--- a/xen/drivers/char/console.c        Tue Apr 14 14:04:58 2009 +0900
+++ b/xen/drivers/char/console.c        Tue Apr 21 12:03:44 2009 +0900
@@ -117,6 +117,8 @@ custom_param("loglvl", parse_loglvl);
 custom_param("loglvl", parse_loglvl);
 custom_param("guest_loglvl", parse_guest_loglvl);

+extern int enable_dom0_con_tasklet;
+
 static atomic_t print_everything = ATOMIC_INIT(0);

 #define ___parse_loglvl(s, ps, lvlstr, lvlnum)          \
@@ -354,7 +356,10 @@ static long guest_console_write(XEN_GUES
         {
             for ( kptr = kbuf; *kptr != '\0'; kptr++ )
                 putchar_console_ring(*kptr);
-            tasklet_schedule(&notify_dom0_con_ring_tasklet);
+              if (enable_dom0_con_tasklet )
+                tasklet_schedule(&notify_dom0_con_ring_tasklet);
+              else
+                send_guest_global_virq(dom0, VIRQ_CON_RING);
         }

         spin_unlock_irq(&console_lock);
@@ -435,7 +440,10 @@ static void __putstr(const char *str)
     {
         while ( (c = *str++) != '\0' )
             putchar_console_ring(c);
-        tasklet_schedule(&notify_dom0_con_ring_tasklet);
+        if (enable_dom0_con_tasklet )
+            tasklet_schedule(&notify_dom0_con_ring_tasklet);
+       else
+            send_guest_global_virq(dom0, VIRQ_CON_RING);
     }
 }


Best Regards,

Akio Takebe

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