On Thu, Aug 16, 2018 at 10:10:55AM -0400, Prarit Bhargava wrote:
> 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)
>
> Signed-off-by: Prarit Bhargava <pra...@redhat.com>
> Cc: Mark Salter <msal...@redhat.com>
> Cc: Al Stone <a...@redhat.com>
> Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
> Cc: Len Brown <len.br...@intel.com>
> Cc: Pavel Machek <pa...@ucw.cz>
> Cc: x...@kernel.org
> Cc: Petr Mladek <pmla...@suse.com>
> Cc: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Kees Cook <keesc...@chromium.org>
> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> Cc: linux...@vger.kernel.org
> ---
> 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);
> +}
<snip>
> +int arch_console_setup(void);
Function does not match its prototype :(
How did you build this successfully?
