New option conring_size= to allow larger console ring.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

4 files changed, 56 insertions, 19 deletions

diff --git a/xen/arch/ia64/xen/xensetup.c b/xen/arch/ia64/xen/xensetup.c
index c3affb4b0d..61b1d11e1c 100644
--- a/xen/arch/ia64/xen/xensetup.c
+++ b/xen/arch/ia64/xen/xensetup.c
@@ -374,7 +374,6 @@ void __init start_kernel(void)
         ns16550_init(0, &ns16550_com1);
         ns16550_init(1, &ns16550_com2);
     }
-    serial_init_preirq();
 
 #ifdef CONFIG_VGA
     /* Plug in a default VGA mode */
@@ -390,7 +389,7 @@ void __init start_kernel(void)
                                         ia64_boot_param->console_info.num_cols;
 #endif
 
-    init_console();
+    console_init_preirq();
 
     if (running_on_sim || ia64_boot_param->domain_start == 0 ||
                           ia64_boot_param->domain_size == 0) {
@@ -648,7 +647,7 @@ printk("num_online_cpus=%d, max_cpus=%d\n",num_online_cpus(),max_cpus);
                 ns16550_init(0, &ns16550_com1);
             }
         }
-        serial_init_postirq();
+        console_init_postirq();
     }
 
     expose_p2m_init();
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 8cf4190144..bf04e43280 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -463,9 +463,7 @@ void __init __start_xen(unsigned long mbi_p)
     ns16550.io_base = 0x2f8;
     ns16550.irq     = 3;
     ns16550_init(1, &ns16550);
-    serial_init_preirq();
-
-    init_console();
+    console_init_preirq();
 
     printk("Command line: %s\n", cmdline);
 
@@ -958,7 +956,7 @@ void __init __start_xen(unsigned long mbi_p)
 
     initialize_keytable();
 
-    serial_init_postirq();
+    console_init_postirq();
 
     for_each_present_cpu ( i )
     {
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index f6ce51aad8..38c540a470 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -58,10 +58,16 @@ boolean_param("console_to_ring", opt_console_to_ring);
 static int opt_console_timestamps;
 boolean_param("console_timestamps", opt_console_timestamps);
 
-#define CONRING_SIZE 16384
-#define CONRING_IDX_MASK(i) ((i)&(CONRING_SIZE-1))
-static char conring[CONRING_SIZE];
-static uint32_t conringc, conringp;
+/* conring_size: allows a large console ring than default (16kB). */
+static uint32_t opt_conring_size;
+static void parse_conring_size(char *s)
+{ opt_conring_size = parse_size_and_unit(s, NULL); }
+custom_param("conring_size", parse_conring_size);
+
+#define _CONRING_SIZE 16384
+#define CONRING_IDX_MASK(i) ((i)&(conring_size-1))
+static char _conring[_CONRING_SIZE], *conring = _conring;
+static uint32_t conring_size = _CONRING_SIZE, conringc, conringp;
 
 static int sercon_handle = -1;
 
@@ -178,8 +184,8 @@ static void putchar_console_ring(int c)
 {
     ASSERT(spin_is_locked(&console_lock));
     conring[CONRING_IDX_MASK(conringp++)] = c;
-    if ( (uint32_t)(conringp - conringc) > CONRING_SIZE )
-        conringc = conringp - CONRING_SIZE;
+    if ( (uint32_t)(conringp - conringc) > conring_size )
+        conringc = conringp - conring_size;
 }
 
 long read_console_ring(struct xen_sysctl_readconsole *op)
@@ -199,8 +205,8 @@ long read_console_ring(struct xen_sysctl_readconsole *op)
     {
         idx = CONRING_IDX_MASK(c);
         len = conringp - c;
-        if ( (idx + len) > CONRING_SIZE )
-            len = CONRING_SIZE - idx;
+        if ( (idx + len) > conring_size )
+            len = conring_size - idx;
         if ( (sofar + len) > max )
             len = max - sofar;
         if ( copy_to_guest_offset(str, sofar, &conring[idx], len) )
@@ -212,8 +218,8 @@ long read_console_ring(struct xen_sysctl_readconsole *op)
     if ( op->clear )
     {
         spin_lock_irq(&console_lock);
-        if ( (uint32_t)(conringp - c) > CONRING_SIZE )
-            conringc = conringp - CONRING_SIZE;
+        if ( (uint32_t)(conringp - c) > conring_size )
+            conringc = conringp - conring_size;
         else
             conringc = c;
         spin_unlock_irq(&console_lock);
@@ -544,10 +550,12 @@ void printk(const char *fmt, ...)
     local_irq_restore(flags);
 }
 
-void __init init_console(void)
+void __init console_init_preirq(void)
 {
     char *p;
 
+    serial_init_preirq();
+
     /* Where should console output go? */
     for ( p = opt_console; p != NULL; p = strchr(p, ',') )
     {
@@ -587,6 +595,37 @@ void __init init_console(void)
     }
 }
 
+void __init console_init_postirq(void)
+{
+    char *ring;
+    unsigned int i;
+
+    serial_init_postirq();
+
+    /* Round size down to a power of two. */
+    while ( opt_conring_size & (opt_conring_size - 1) )
+        opt_conring_size &= opt_conring_size - 1;
+    if ( opt_conring_size < conring_size )
+        return;
+    
+    ring = xmalloc_bytes(opt_conring_size);
+    if ( ring == NULL )
+    {
+        printk("Unable to allocate console ring of %u bytes.\n",
+               opt_conring_size);
+        return;
+    }
+
+    spin_lock_irq(&console_lock);
+    for ( i = conringc ; i != conringp; i++ )
+        ring[i & (opt_conring_size - 1)] = conring[i & (conring_size - 1)];
+    conring_size = opt_conring_size;
+    conring = ring;
+    spin_unlock_irq(&console_lock);
+
+    printk("Allocated console ring of %u bytes.\n", opt_conring_size);
+}
+
 void __init console_endboot(void)
 {
     int i, j;
diff --git a/xen/include/xen/console.h b/xen/include/xen/console.h
index 5817f74958..50dd1e582e 100644
--- a/xen/include/xen/console.h
+++ b/xen/include/xen/console.h
@@ -14,7 +14,8 @@
 struct xen_sysctl_readconsole;
 long read_console_ring(struct xen_sysctl_readconsole *op);
 
-void init_console(void);
+void console_init_preirq(void);
+void console_init_postirq(void);
 void console_endboot(void);
 int console_has(const char *device);