ACPI may contain an SPCR table that defines a default system console. On ARM if the table is present then the SPCR console is enabled by default. On x86 the SPCR console is used if 'earlycon' (no parameters) is specified as a kernel parameter and is used only as the early console. To use the SPCR data as a console a user must boot with 'earlycon', grep logs & specify a console= kernel parameter, and then reboot again.
Add 'console=auto' that enables a firmware or hardware console, and on x86 enable the SPCR console if 'console=auto' is specified. Tested on systems with and without an ACPI SPCR. The following kernel parameters were also tested: console=ttyS0,115200 works earlycon works (early console only) console=auto works (full console as expected) no console or earlycon arguments works (no output as expected) v2: Fix prototype. Signed-off-by: Prarit Bhargava <[email protected]> Cc: Mark Salter <[email protected]> Cc: Al Stone <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> Cc: Len Brown <[email protected]> Cc: Pavel Machek <[email protected]> Cc: [email protected] Cc: Petr Mladek <[email protected]> Cc: Sergey Senozhatsky <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Kees Cook <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: [email protected] --- Documentation/admin-guide/kernel-parameters.txt | 1 + arch/x86/kernel/acpi/boot.c | 5 +++++ include/linux/console.h | 1 + kernel/printk/printk.c | 10 ++++++++++ 4 files changed, 17 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a32f2a126791..dd057224f33b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -635,6 +635,7 @@ hvc<n> Use the hypervisor console device <n>. This is for both Xen and PowerPC hypervisors. + auto [X86] Enable ACPI SPCR console If the device connected to the port is not a TTY but a braille device, prepend "brl," before the device type, for instance diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 3b20607d581b..fb2616ba3b21 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -1771,3 +1771,8 @@ void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size) e820__range_add(addr, size, E820_TYPE_ACPI); e820__update_table_print(); } + +void __init arch_console_setup(void) +{ + acpi_parse_spcr(false, true); +} diff --git a/include/linux/console.h b/include/linux/console.h index dfd6b0e97855..c2a6dde9a799 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -181,6 +181,7 @@ extern int is_console_locked(void); extern int braille_register_console(struct console *, int index, char *console_options, char *braille_options); extern int braille_unregister_console(struct console *); +void arch_console_setup(void); #ifdef CONFIG_TTY extern void console_sysfs_notify(void); #else diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 247808333ba4..bdd53858664b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2078,6 +2078,11 @@ static int __init console_msg_format_setup(char *str) } __setup("console_msg_format=", console_msg_format_setup); +void __init __weak arch_console_setup(void) +{ + return; +} + /* * Set up a console. Called via do_early_param() in init/main.c * for each "console=" parameter in the boot command line. @@ -2088,6 +2093,11 @@ static int __init console_setup(char *str) char *s, *options, *brl_options = NULL; int idx; + if (!strcmp(str, "auto")) { + arch_console_setup(); + return 1; + } + if (_braille_console_setup(&str, &brl_options)) return 1; -- 2.14.4
