@@ -433,6 +433,9 @@ only available when used together with `pv-in-pvh`.
`none` indicates that Xen should not use a console. This option only
makes sense on its own.
+Specifying more than one serial console will increase console latency,
+especially when `sync_console` option is used.
+
### console_timestamps
> `= none | date | datems | boot | raw`
@@ -2390,6 +2393,7 @@ vulnerabilities.
Flag to force synchronous console output. Useful for debugging, but
not suitable for production environments due to incurred overhead.
+If multiple consoles are configured, the incurred overhead is even bigger.
### tboot (x86)
> `= 0x<phys_addr>`
@@ -85,6 +85,17 @@ config SERIAL_TX_BUFSIZE
Default value is 16384 (16kiB).
+config MAX_SERCONS
+ int "Maximum number of serial consoles active at once"
+ default 4
+ help
+ Controls how many serial consoles can be active at once. Configuring more
+ using `console=` parameter will be ignored.
+ When multiple consoles are configured, overhead of `sync_console` option
+ is even bigger.
+
+ Default value is 4.
+
config XHCI
bool "XHCI DbC UART driver"
depends on X86
@@ -113,7 +113,9 @@ static char *__read_mostly conring = _conring;
static uint32_t __read_mostly conring_size = _CONRING_SIZE;
static uint32_t conringc, conringp;
-static int __read_mostly sercon_handle = -1;
+#define MAX_SERCONS CONFIG_MAX_SERCONS
+static int __read_mostly sercon_handle[MAX_SERCONS];
+static unsigned int __read_mostly nr_sercon_handle = 0;
#ifdef CONFIG_X86
/* Tristate: 0 disabled, 1 user enabled, -1 default enabled */
@@ -393,32 +395,61 @@ long read_console_ring(struct xen_sysctl_readconsole *op)
static char serial_rx_ring[SERIAL_RX_SIZE];
static unsigned int serial_rx_cons, serial_rx_prod;
-static void (*serial_steal_fn)(const char *, size_t nr) = early_puts;
+/* The last entry means "steal from all consoles" */
+static void (*serial_steal_fn[])(const char *, size_t nr) = {
+ [MAX_SERCONS] = early_puts,
+};
+/*
+ * Redirect console *handle* output to *fn*. Use SERHND_STEAL_ALL as *handle* to
+ * redirect all the consoles.
+ */
int console_steal(int handle, void (*fn)(const char *, size_t nr))
{
- if ( (handle == -1) || (handle != sercon_handle) )
- return 0;
+ unsigned int i;
+
+ if ( handle == -1 )
+ return -ENOENT;
+ if ( serial_steal_fn[MAX_SERCONS] != NULL )
+ return -EBUSY;
+ if ( handle == SERHND_STEAL_ALL )
+ {
+ serial_steal_fn[MAX_SERCONS] = fn;
+ return MAX_SERCONS;
+ }
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ if ( handle == sercon_handle[i] )
+ break;
+ if ( i == nr_sercon_handle )
+ return -ENOENT;
- if ( serial_steal_fn != NULL )
+ if ( serial_steal_fn[i] != NULL )
return -EBUSY;
- serial_steal_fn = fn;
- return 1;
+ serial_steal_fn[i] = fn;
+ return i;
}
void console_giveback(int id)
{
- if ( id == 1 )
- serial_steal_fn = NULL;
+ if ( id >= 0 && id <= MAX_SERCONS )
+ serial_steal_fn[id] = NULL;
}
void console_serial_puts(const char *s, size_t nr)
{
- if ( serial_steal_fn != NULL )
- serial_steal_fn(s, nr);
+ unsigned int i;
+
+ if ( serial_steal_fn[MAX_SERCONS] != NULL )
+ serial_steal_fn[MAX_SERCONS](s, nr);
else
- serial_puts(sercon_handle, s, nr);
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ {
+ if ( serial_steal_fn[i] != NULL )
+ serial_steal_fn[i](s, nr);
+ else
+ serial_puts(sercon_handle[i], s, nr);
+ }
/* Copy all serial output into PV console */
pv_console_puts(s, nr);
@@ -957,6 +988,7 @@ void __init console_init_preirq(void)
{
char *p;
int sh;
+ unsigned int i;
serial_init_preirq();
@@ -977,8 +1009,12 @@ void __init console_init_preirq(void)
continue;
else if ( (sh = serial_parse_handle(p)) >= 0 )
{
- sercon_handle = sh;
- serial_steal_fn = NULL;
+ if ( nr_sercon_handle < MAX_SERCONS )
+ sercon_handle[nr_sercon_handle++] = sh;
+ else
+ printk("Too many consoles (max %d), ignoring '%s'\n",
+ MAX_SERCONS, p);
+ serial_steal_fn[MAX_SERCONS] = NULL;
}
else
{
@@ -996,7 +1032,8 @@ void __init console_init_preirq(void)
opt_console_xen = 0;
#endif
- serial_set_rx_handler(sercon_handle, serial_rx);
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ serial_set_rx_handler(sercon_handle[i], serial_rx);
pv_console_set_rx_handler(serial_rx);
/* HELLO WORLD --- start-of-day banner text. */
@@ -1014,7 +1051,8 @@ void __init console_init_preirq(void)
if ( opt_sync_console )
{
- serial_start_sync(sercon_handle);
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ serial_start_sync(sercon_handle[i]);
add_taint(TAINT_SYNC_CONSOLE);
printk("Console output is synchronous.\n");
warning_add(warning_sync_console);
@@ -1121,13 +1159,19 @@ int __init console_has(const char *device)
void console_start_log_everything(void)
{
- serial_start_log_everything(sercon_handle);
+ unsigned int i;
+
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ serial_start_log_everything(sercon_handle[i]);
atomic_inc(&print_everything);
}
void console_end_log_everything(void)
{
- serial_end_log_everything(sercon_handle);
+ unsigned int i;
+
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ serial_end_log_everything(sercon_handle[i]);
atomic_dec(&print_everything);
}
@@ -1149,23 +1193,32 @@ void console_unlock_recursive_irqrestore(unsigned long flags)
void console_force_unlock(void)
{
+ unsigned int i;
+
watchdog_disable();
spin_debug_disable();
spin_lock_init(&console_lock);
- serial_force_unlock(sercon_handle);
+ for ( i = 0 ; i < nr_sercon_handle ; i++ )
+ serial_force_unlock(sercon_handle[i]);
console_locks_busted = 1;
console_start_sync();
}
void console_start_sync(void)
{
+ unsigned int i;
+
atomic_inc(&print_everything);
- serial_start_sync(sercon_handle);
+ for ( i = 0 ; i < nr_sercon_handle ; i++ )
+ serial_start_sync(sercon_handle[i]);
}
void console_end_sync(void)
{
- serial_end_sync(sercon_handle);
+ unsigned int i;
+
+ for ( i = 0; i < nr_sercon_handle; i++ )
+ serial_end_sync(sercon_handle[i]);
atomic_dec(&print_everything);
}
@@ -1291,7 +1344,8 @@ static int suspend_steal_id;
int console_suspend(void)
{
- suspend_steal_id = console_steal(sercon_handle, suspend_steal_fn);
+ if ( nr_sercon_handle )
+ suspend_steal_id = console_steal(SERHND_STEAL_ALL, suspend_steal_fn);
serial_suspend();
return 0;
}
@@ -99,6 +99,7 @@ struct uart_driver {
#define SERHND_HI (1<<2) /* Mux/demux each transferred char by MSB. */
#define SERHND_LO (1<<3) /* Ditto, except that the MSB is cleared. */
#define SERHND_COOKED (1<<4) /* Newline/carriage-return translation? */
+#define SERHND_STEAL_ALL 0xff /* Synthetic handle used in console_steal() */
/* Three-stage initialisation (before/during/after IRQ-subsystem setup). */
void serial_init_preirq(void);
Previously only one serial console was supported at the same time. Using console=com1,dbgp,vga silently ignored all but last serial console (in this case: only dbgp and vga were active). Fix this by storing not a single sercon_handle, but an array of them, up to MAX_SERCONS entries. The value of MAX_SERCONS can be chosen in kconfig, the default (4) is arbitrary, inspired by the number of SERHND_IDX values. Make console_steal() aware of multiple consoles too. It can now either steal output from specific console (for gdbstub), or from all of them at once (for console suspend). Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> --- Changes in v4: - use unsigned int for loop counters - other minor changes Changes in v3: - adjust console_steal() for multiple consoles too - add MAX_SERCONS to kconfig - add warning about sync_console impact - add warning if too many consoles are configured - log issue with PCI spec parsing --- docs/misc/xen-command-line.pandoc | 4 +- xen/drivers/char/Kconfig | 11 ++++- xen/drivers/char/console.c | 98 ++++++++++++++++++++++++-------- xen/include/xen/serial.h | 1 +- 4 files changed, 92 insertions(+), 22 deletions(-)