[Xen-devel] [PATCH] console: allocate ring buffer earlier

["Jan Beulich" <JBeulich@xxxxxxxx>]

... when "conring_size=" was specified on the command line. We can't
really do this as early as we would want to when the option was not
specified, as the default depends on knowing the system CPU count. Yet
the parsing of the ACPI tables is one of the things that generates a
lot of output especially on large systems.

I didn't change ARM, as I wasn't sure how far ahead this call could be
pulled.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1187,6 +1187,7 @@ void __init noreturn __start_xen(unsigne
     }
 
     vm_init();
+    console_init_mem();
     vesa_init();
 
     softirq_init();
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -744,15 +744,14 @@ void __init console_init_preirq(void)
     }
 }
 
-void __init console_init_postirq(void)
+void __init console_init_mem(void)
 {
     char *ring;
     unsigned int i, order, memflags;
-
-    serial_init_postirq();
+    unsigned long flags;
 
     if ( !opt_conring_size )
-        opt_conring_size = num_present_cpus() << (9 + xenlog_lower_thresh);
+        return;
 
     order = get_order_from_bytes(max(opt_conring_size, conring_size));
     memflags = MEMF_bits(crashinfo_maxaddr_bits);
@@ -763,17 +762,28 @@ void __init console_init_postirq(void)
     }
     opt_conring_size = PAGE_SIZE << order;
 
-    spin_lock_irq(&console_lock);
+    spin_lock_irqsave(&console_lock, flags);
     for ( i = conringc ; i != conringp; i++ )
         ring[i & (opt_conring_size - 1)] = conring[i & (conring_size - 1)];
     conring = ring;
     smp_wmb(); /* Allow users of console_force_unlock() to see larger buffer. 
*/
     conring_size = opt_conring_size;
-    spin_unlock_irq(&console_lock);
+    spin_unlock_irqrestore(&console_lock, flags);
 
     printk("Allocated console ring of %u KiB.\n", opt_conring_size >> 10);
 }
 
+void __init console_init_postirq(void)
+{
+    serial_init_postirq();
+
+    if ( !opt_conring_size )
+        opt_conring_size = num_present_cpus() << (9 + xenlog_lower_thresh);
+
+    if ( conring == _conring )
+        console_init_mem();
+}
+
 void __init console_endboot(void)
 {
     int i, j;
--- a/xen/include/xen/console.h
+++ b/xen/include/xen/console.h
@@ -14,6 +14,7 @@ struct xen_sysctl_readconsole;
 long read_console_ring(struct xen_sysctl_readconsole *op);
 
 void console_init_preirq(void);
+void console_init_mem(void);
 void console_init_postirq(void);
 void console_endboot(void);
 int console_has(const char *device);

Attachment: conring-alloc-earlier.patch
Description: Text document

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