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| author | Yinghai Lu <Yinghai.Lu@Sun.COM> | 2007-07-15 23:37:59 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-16 09:05:35 -0700 |
| commit | 18a8bd949d6adb311ea816125ff65050df1f3f6e (patch) | |
| tree | 4365db908430747a5c08cacdb4354577b7bfead7 /Documentation/kernel-parameters.txt | |
| parent | b1c931e39327ef121797927d4b3198d370e75b9b (diff) | |
| download | lwn-18a8bd949d6adb311ea816125ff65050df1f3f6e.tar.gz lwn-18a8bd949d6adb311ea816125ff65050df1f3f6e.zip | |
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@sun.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4d880b3d1f35..62aab585d9d7 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -462,13 +462,20 @@ 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] + uart[8250],io,<addr>[,options] + uart[8250],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. + uart[8250],io,<addr>[,options] + uart[8250],mmio,<addr>[,options] + Start an early, polled-mode console on the 8250/16550 + UART at the specified I/O port or MMIO address. + The options are the same as for ttyS, above. + cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] |