PATCH] serial: convert early_uart to earlycon for 8250

From: Yinghai Lu
Date: Tue May 22 2007 - 15:33:43 EST

PATCH] serial: convert early_uart to earlycon for 8250

Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and
include/asm-x86_64/serial.h. the serial8250_ports need to be probed late
in serial initializing stage. the console_init=>serial8250_console_init=>
register_console=>serial8250_console_setup will return -ENDEV, and console
ttyS0 can not be enabled at that time.
need to wait till uart_add_one_port in drivers/serial/serial_core.c to call
register_console to get console ttyS0. that is too late.

Make early_uart to use early_param, so uart console can be used earlier.
Make it to be bootconsole with CON_BOOT flag, so can use console handover
feature. and it will switch to corresponding normal serial console
automatically.

new command line will be:
console=uart8250,io,0x3f8,9600n8
console=uart8250,mmio,0xff5e0000,115200n8
or
earlycon=uart8250,io,0x3f8,9600n8
earlycon=uart8250,mmio,0xff5e0000,115200n8

it will print in very early stage:
Early serial console at I/O port 0x3f8 (options '9600n8')
console [uart0] enabled
later for console it will print:
console handover: boot [uart0] -> real [ttyS0]

Signed-off-by: <yinghai.lu@xxxxxxx>

Documentation/kernel-parameters.txt | 12 +++-
arch/i386/kernel/head.S | 8 ++
arch/ia64/kernel/setup.c | 4 -
arch/x86_64/kernel/head.S | 15 ++++-
drivers/serial/8250.c | 26 +--------
drivers/serial/8250_early.c | 103 ++++++++++++++----------------------
drivers/serial/Kconfig | 8 ++
drivers/serial/serial_core.c | 5 +
include/asm-i386/fixmap.h | 2
include/asm-i386/io.h | 13 ++++
include/asm-ia64/io.h | 4 +
include/asm-x86_64/fixmap.h | 4 +
include/asm-x86_64/io.h | 13 ++++
include/linux/console.h | 1
include/linux/serial.h | 6 --
include/linux/serial_8250.h | 3 +
include/linux/serial_core.h | 5 +
init/main.c | 5 +
kernel/printk.c | 17 +++++
19 files changed, 156 insertions(+), 98 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 09220a1..634d809 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -444,8 +444,16 @@ and is between 256 and 4096 characters. It is defined in the file
Documentation/networking/netconsole.txt for an
alternative.

- uart,io,<addr>[,options]
- uart,mmio,<addr>[,options]
+ uart8250,io,<addr>[,options]
+ uart8250,mmio,<addr>[,options]
+ Start an early, polled-mode console on the 8250/16550
+ UART at the specified I/O port or MMIO address,
+ switching to the matching ttyS device later. The
+ options are the same as for ttyS, above.
+
+ earlycon= [KNL] Output early console device and options.
+ uart8250,io,<addr>[,options]
+ uart8250,mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
switching to the matching ttyS device later. The
diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index f74dfc4..8271466 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -168,6 +168,12 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
.section .init.text,"ax",@progbits
#endif

+ /* Do an early initialization of the fixmap area */
+ movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
+ movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
+ addl $0x007, %eax /* 0x007 = PRESENT+RW+USER */
+ movl %eax, 4092(%edx)
+
#ifdef CONFIG_SMP
ENTRY(startup_32_smp)
cld
@@ -507,6 +513,8 @@ ENTRY(_stext)
.section ".bss.page_aligned","w"
ENTRY(swapper_pg_dir)
.fill 1024,4,0
+ENTRY(swapper_pg_pmd)
+ .fill 1024,4,0
ENTRY(empty_zero_page)
.fill 4096,1,0

diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index eaa6a24..dd7f95b 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -390,10 +390,6 @@ early_console_setup (char *cmdline)
if (!efi_setup_pcdp_console(cmdline))
earlycons++;
#endif
-#ifdef CONFIG_SERIAL_8250_CONSOLE
- if (!early_serial_console_init(cmdline))
- earlycons++;
-#endif

return (earlycons) ? 0 : -1;
}
diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 1fab487..941c84b 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -73,7 +73,11 @@ startup_64:
addq %rbp, init_level4_pgt + (511*8)(%rip)

addq %rbp, level3_ident_pgt + 0(%rip)
+
addq %rbp, level3_kernel_pgt + (510*8)(%rip)
+ addq %rbp, level3_kernel_pgt + (511*8)(%rip)
+
+ addq %rbp, level2_fixmap_pgt + (506*8)(%rip)

/* Add an Identity mapping if I am above 1G */
leaq _text(%rip), %rdi
@@ -314,7 +318,16 @@ NEXT_PAGE(level3_kernel_pgt)
.fill 510,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
.quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
- .fill 1,8,0
+ .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
+
+NEXT_PAGE(level2_fixmap_pgt)
+ .fill 506,8,0
+ .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
+ /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
+ .fill 5,8,0
+
+NEXT_PAGE(level1_fixmap_pgt)
+ .fill 512,8,0

NEXT_PAGE(level2_ident_pgt)
/* Since I easily can, map the first 1G.
diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index c84dab0..e341fb9 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2367,6 +2367,9 @@ static struct uart_ops serial8250_pops = {
.request_port = serial8250_request_port,
.config_port = serial8250_config_port,
.verify_port = serial8250_verify_port,
+#ifdef CONFIG_SERIAL_8250_CONSOLE
+ .find_port_for_earlycon = serial8250_find_port_for_earlycon,
+#endif
};

static struct uart_8250_port serial8250_ports[UART_NR];
@@ -2402,6 +2405,7 @@ static void __init serial8250_isa_init_ports(void)
for (i = 0, up = serial8250_ports;
i < ARRAY_SIZE(old_serial_port) && i < nr_uarts;
i++, up++) {
+ printk(KERN_INFO "serial8250_isa_init_ports 2 idx=%d\n",i);
up->port.iobase = old_serial_port[i].port;
up->port.irq = irq_canonicalize(old_serial_port[i].irq);
up->port.uartclk = old_serial_port[i].baud_base * 16;
@@ -2533,7 +2537,7 @@ static int __init serial8250_console_init(void)
}
console_initcall(serial8250_console_init);

-static int __init find_port(struct uart_port *p)
+int __init find_port_serial8250(struct uart_port *p)
{
int line;
struct uart_port *port;
@@ -2546,26 +2550,6 @@ static int __init find_port(struct uart_port *p)
return -ENODEV;
}

-int __init serial8250_start_console(struct uart_port *port, char *options)
-{
- int line;
-
- line = find_port(port);
- if (line < 0)
- return -ENODEV;
-
- add_preferred_console("ttyS", line, options);
- printk("Adding console on ttyS%d at %s 0x%lx (options '%s')\n",
- line, port->iotype == UPIO_MEM ? "MMIO" : "I/O port",
- port->iotype == UPIO_MEM ? (unsigned long) port->mapbase :
- (unsigned long) port->iobase, options);
- if (!(serial8250_console.flags & CON_ENABLED)) {
- serial8250_console.flags &= ~CON_PRINTBUFFER;
- register_console(&serial8250_console);
- }
- return line;
-}
-
#define SERIAL8250_CONSOLE &serial8250_console
#else
#define SERIAL8250_CONSOLE NULL
diff --git a/drivers/serial/8250_early.c b/drivers/serial/8250_early.c
index 7e51119..7063a81 100644
--- a/drivers/serial/8250_early.c
+++ b/drivers/serial/8250_early.c
@@ -17,13 +17,11 @@
* we locate the device directly by its MMIO or I/O port address.
*
* The user can specify the device directly, e.g.,
- * console=uart,io,0x3f8,9600n8
- * console=uart,mmio,0xff5e0000,115200n8
- * or platform code can call early_uart_console_init() to set
- * the early UART device.
- *
- * After the normal serial driver starts, we try to locate the
- * matching ttyS device and start a console there.
+ * earlycon=uart8250,io,0x3f8,9600n8
+ * earlycon=uart8250,mmio,0xff5e0000,115200n8
+ * or
+ * console=uart8250,io,0x3f8,9600n8
+ * console=uart8250,mmio,0xff5e0000,115200n8
*/

#include <linux/tty.h>
@@ -32,17 +30,17 @@
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/serial.h>
+#include <linux/serial_8250.h>
#include <asm/io.h>
#include <asm/serial.h>

-struct early_uart_device {
+struct early_serial8250_device {
struct uart_port port;
char options[16]; /* e.g., 115200n8 */
unsigned int baud;
};

-static struct early_uart_device early_device __initdata;
-static int early_uart_registered __initdata;
+static struct early_serial8250_device early_device __initdata;

static unsigned int __init serial_in(struct uart_port *port, int offset)
{
@@ -80,7 +78,7 @@ static void __init putc(struct uart_port *port, int c)
serial_out(port, UART_TX, c);
}

-static void __init early_uart_write(struct console *console, const char *s, unsigned int count)
+static void __init early_serial8250_write(struct console *console, const char *s, unsigned int count)
{
struct uart_port *port = &early_device.port;
unsigned int ier;
@@ -111,7 +109,7 @@ static unsigned int __init probe_baud(struct uart_port *port)
return (port->uartclk / 16) / quot;
}

-static void __init init_port(struct early_uart_device *device)
+static void __init init_port(struct early_serial8250_device *device)
{
struct uart_port *port = &device->port;
unsigned int divisor;
@@ -130,10 +128,9 @@ static void __init init_port(struct early_uart_device *device)
serial_out(port, UART_LCR, c & ~UART_LCR_DLAB);
}

-static int __init parse_options(struct early_uart_device *device, char *options)
+static int __init parse_options(struct early_serial8250_device *device, char *options)
{
struct uart_port *port = &device->port;
- int mapsize = 64;
int mmio, length;

if (!options)
@@ -143,12 +140,7 @@ static int __init parse_options(struct early_uart_device *device, char *options)
if (!strncmp(options, "mmio,", 5)) {
port->iotype = UPIO_MEM;
port->mapbase = simple_strtoul(options + 5, &options, 0);
- port->membase = ioremap(port->mapbase, mapsize);
- if (!port->membase) {
- printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
- __FUNCTION__, port->mapbase);
- return -ENOMEM;
- }
+ port->membase = fix_ioremap(FIX_EARLYCON_MEM_BASE, port->mapbase);
mmio = 1;
} else if (!strncmp(options, "io,", 3)) {
port->iotype = UPIO_PORT;
@@ -175,9 +167,16 @@ static int __init parse_options(struct early_uart_device *device, char *options)
return 0;
}

-static int __init early_uart_setup(struct console *console, char *options)
+static struct console early_serial8250_console __initdata = {
+ .name = "uart",
+ .write = early_serial8250_write,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
+
+static int __init early_serial8250_setup(char *options)
{
- struct early_uart_device *device = &early_device;
+ struct early_serial8250_device *device = &early_device;
int err;

if (device->port.membase || device->port.iobase)
@@ -190,61 +189,43 @@ static int __init early_uart_setup(struct console *console, char *options)
return 0;
}

-static struct console early_uart_console __initdata = {
- .name = "uart",
- .write = early_uart_write,
- .setup = early_uart_setup,
- .flags = CON_PRINTBUFFER,
- .index = -1,
-};
-
-static int __init early_uart_console_init(void)
-{
- if (!early_uart_registered) {
- register_console(&early_uart_console);
- early_uart_registered = 1;
- }
- return 0;
-}
-console_initcall(early_uart_console_init);
-
-int __init early_serial_console_init(char *cmdline)
+static int __init setup_early_serial8250_console(char *cmdline)
{
char *options;
int err;

- options = strstr(cmdline, "console=uart,");
+ options = strstr(cmdline, "uart8250,");
if (!options)
- return -ENODEV;
+ return 0;

options = strchr(cmdline, ',') + 1;
- if ((err = early_uart_setup(NULL, options)) < 0)
+ if ((err = early_serial8250_setup(options)) < 0)
return err;
- return early_uart_console_init();
+
+ early_serial8250_console.flags |= CON_BOOT;
+ register_console(&early_serial8250_console);
+
+ /* add one dummy entry in console_cmdline*/
+ add_preferred_console("ttyS", 255, early_device.options);
+
+ return 0;
}

-static int __init early_uart_console_switch(void)
+int serial8250_find_port_for_earlycon(void)
{
- struct early_uart_device *device = &early_device;
+ struct early_serial8250_device *device = &early_device;
struct uart_port *port = &device->port;
- int mmio, line;
+ int line;

- if (!(early_uart_console.flags & CON_ENABLED))
- return 0;
+ line = find_port_serial8250(port);

- /* Try to start the normal driver on a matching line. */
- mmio = (port->iotype == UPIO_MEM);
- line = serial8250_start_console(port, device->options);
if (line < 0)
- printk("No ttyS device at %s 0x%lx for console\n",
- mmio ? "MMIO" : "I/O port",
- mmio ? port->mapbase :
- (unsigned long) port->iobase);
+ return -ENODEV;

- unregister_console(&early_uart_console);
- if (mmio)
- iounmap(port->membase);
+ /* update the dummy entry to what we want console type */
+ update_console_cmdline_console_index("ttyS", 255, line);

return 0;
}
-late_initcall(early_uart_console_switch);
+
+early_param("earlycon", setup_early_serial8250_console);
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 315ea99..4206ace 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -62,6 +62,14 @@ config SERIAL_8250_CONSOLE
kernel will automatically use the first serial line, /dev/ttyS0, as
system console.

+ you can set that using a kernel command line option such as
+ "earlycon=uart8250,io,0x3f8,9600n8"
+ "earlycon=uart8250,mmio,0xff5e0000,115200n8" or
+ "console=uart8250,io,0x3f8,9600n8"
+ "console=uart8250,mmio,0xff5e0000,115200n8".
+ and it will switch to normal serial console when correponding port is
+ ready.
+
If unsure, say N.

config SERIAL_8250_GSC
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 326020f..4f60767 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2303,8 +2303,11 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
* It may be that the port was not available.
*/
if (port->type != PORT_UNKNOWN &&
- port->cons && !(port->cons->flags & CON_ENABLED))
+ port->cons && !(port->cons->flags & CON_ENABLED)) {
+ if(port->ops && port->ops->find_port_for_earlycon)
+ port->ops->find_port_for_earlycon();
register_console(port->cons);
+ }

/*
* Ensure UPF_DEAD is not set.
diff --git a/include/asm-i386/fixmap.h b/include/asm-i386/fixmap.h
index 80ea052..249e753 100644
--- a/include/asm-i386/fixmap.h
+++ b/include/asm-i386/fixmap.h
@@ -54,6 +54,8 @@ extern unsigned long __FIXADDR_TOP;
enum fixed_addresses {
FIX_HOLE,
FIX_VDSO,
+ FIX_DBGP_BASE,
+ FIX_EARLYCON_MEM_BASE,
#ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
#endif
diff --git a/include/asm-i386/io.h b/include/asm-i386/io.h
index e797586..6c8748d 100644
--- a/include/asm-i386/io.h
+++ b/include/asm-i386/io.h
@@ -130,6 +130,19 @@ extern void iounmap(volatile void __iomem *addr);
extern void *bt_ioremap(unsigned long offset, unsigned long size);
extern void bt_iounmap(void *addr, unsigned long size);

+#include <asm/pgtable.h>
+#include <asm/fixmap.h>
+
+static inline void __iomem * fix_ioremap (unsigned idx, unsigned long phys)
+{
+ void __iomem * vaddr;
+ set_fixmap_nocache(idx, phys & PAGE_MASK);
+ vaddr = (void __iomem *)__fix_to_virt(idx);
+ vaddr += phys & ~PAGE_MASK;
+
+ return vaddr;
+}
+
/* Use early IO mappings for DMI because it's initialized early */
#define dmi_ioremap bt_ioremap
#define dmi_iounmap bt_iounmap
diff --git a/include/asm-ia64/io.h b/include/asm-ia64/io.h
index eb17a86..e29eaf8 100644
--- a/include/asm-ia64/io.h
+++ b/include/asm-ia64/io.h
@@ -423,6 +423,10 @@ extern void __iomem * ioremap(unsigned long offset, unsigned long size);
extern void __iomem * ioremap_nocache (unsigned long offset, unsigned long size);
extern void iounmap (volatile void __iomem *addr);

+/* for console=uart8250,mmio,0xffe5000,9600n8 */
+#define FIX_EARLYCON_MEM_BASE 1
+#define fix_ioremap(idx, phys) ioremap(phys, 64)
+
/* Use normal IO mappings for DMI */
#define dmi_ioremap ioremap
#define dmi_iounmap(x,l) iounmap(x)
diff --git a/include/asm-x86_64/fixmap.h b/include/asm-x86_64/fixmap.h
index e90e167..2acb9b7 100644
--- a/include/asm-x86_64/fixmap.h
+++ b/include/asm-x86_64/fixmap.h
@@ -35,6 +35,8 @@ enum fixed_addresses {
VSYSCALL_LAST_PAGE,
VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
VSYSCALL_HPET,
+ FIX_DBGP_BASE,
+ FIX_EARLYCON_MEM_BASE,
FIX_HPET_BASE,
FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
FIX_IO_APIC_BASE_0,
@@ -84,7 +86,7 @@ static __always_inline unsigned long fix_to_virt(const unsigned int idx)
if (idx >= __end_of_fixed_addresses)
__this_fixmap_does_not_exist();

- return __fix_to_virt(idx);
+ return __fix_to_virt(idx);
}

#endif
diff --git a/include/asm-x86_64/io.h b/include/asm-x86_64/io.h
index de2cd9a..e2d66de 100644
--- a/include/asm-x86_64/io.h
+++ b/include/asm-x86_64/io.h
@@ -145,6 +145,19 @@ extern void early_iounmap(void *addr, unsigned long size);
extern void __iomem * ioremap_nocache (unsigned long offset, unsigned long size);
extern void iounmap(volatile void __iomem *addr);

+#include <asm/pgtable.h>
+#include <asm/fixmap.h>
+
+static inline void __iomem * fix_ioremap (unsigned idx, unsigned long phys)
+{
+ void __iomem * vaddr;
+ set_fixmap_nocache(idx, phys & PAGE_MASK);
+ vaddr = (void __iomem *)__fix_to_virt(idx);
+ vaddr += phys & ~PAGE_MASK;
+
+ return vaddr;
+}
+
/*
* ISA I/O bus memory addresses are 1:1 with the physical address.
*/
diff --git a/include/linux/console.h b/include/linux/console.h
index 62ef6e1..4cb7749 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -107,6 +107,7 @@ struct console {
};

extern int add_preferred_console(char *name, int idx, char *options);
+extern int update_console_cmdline_console_index(char *name, int idx_old, int idx_new);
extern void register_console(struct console *);
extern int unregister_console(struct console *);
extern struct console *console_drivers;
diff --git a/include/linux/serial.h b/include/linux/serial.h
index 33fc8cb..deb7143 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -177,11 +177,5 @@ struct serial_icounter_struct {
#ifdef __KERNEL__
#include <linux/compiler.h>

-/* Allow architectures to override entries in serial8250_ports[] at run time: */
-struct uart_port; /* forward declaration */
-extern int early_serial_setup(struct uart_port *port);
-extern int early_serial_console_init(char *options);
-extern int serial8250_start_console(struct uart_port *port, char *options);
-
#endif /* __KERNEL__ */
#endif /* _LINUX_SERIAL_H */
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 71310d8..0d79fc5 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -60,4 +60,7 @@ void serial8250_unregister_port(int line);
void serial8250_suspend_port(int line);
void serial8250_resume_port(int line);

+extern int find_port_serial8250(struct uart_port *p);
+extern int serial8250_find_port_for_earlycon(void);
+
#endif
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index a3ac4c8..ac2b13c 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -199,6 +199,11 @@ struct uart_ops {
void (*config_port)(struct uart_port *, int);
int (*verify_port)(struct uart_port *, struct serial_struct *);
int (*ioctl)(struct uart_port *, unsigned int, unsigned long);
+
+ /*
+ * for earlycon to console switch
+ */
+ int (*find_port_for_earlycon)(void);
};

#define UART_CONFIG_TYPE (1 << 0)
diff --git a/init/main.c b/init/main.c
index eb8bdba..58dbe75 100644
--- a/init/main.c
+++ b/init/main.c
@@ -452,7 +452,10 @@ static int __init do_early_param(char *param, char *val)
struct obs_kernel_param *p;

for (p = __setup_start; p < __setup_end; p++) {
- if (p->early && strcmp(param, p->str) == 0) {
+ if ((p->early && strcmp(param, p->str) == 0) ||
+ (strcmp(param, "console") == 0 &&
+ strcmp(p->str, "earlycon") == 0)
+ ) {
if (p->setup_func(val) != 0)
printk(KERN_WARNING
"Malformed early option '%s'\n", param);
diff --git a/kernel/printk.c b/kernel/printk.c
index 0bbdeac..8f3d91e 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -726,6 +726,20 @@ int __init add_preferred_console(char *name, int idx, char *options)
return 0;
}

+int __init update_console_cmdline_console_index(char *name, int idx_old, int idx_new)
+{
+ int i;
+
+ for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
+ if (strcmp(console_cmdline[i].name, name) == 0 &&
+ console_cmdline[i].index == idx_old) {
+ console_cmdline[i].index = idx_new;
+ return 0;
+ }
+
+ return 0;
+}
+
#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
/**
* suspend_console - suspend the console subsystem
@@ -991,6 +1005,9 @@ void register_console(struct console *console)
console->name, console->index);
unregister_console(bootconsole);
console->flags &= ~CON_PRINTBUFFER;
+ } else {
+ printk(KERN_INFO "console [%s%d] enabled\n",
+ console->name, console->index);
}

/*
-
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