On Thu, 16 Aug 2018 11:28:24 -0400
Prarit Bhargava <pra...@redhat.com> wrote:
> On 08/16/2018 11:09 AM, Greg Kroah-Hartman wrote:
> > 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?
>
> Weird, it compiles on my system?
Are you compiling with ACPI enabled?
It would still compile without it and use the properly prototyped
"weak" function.
-- Steve
>
> I'll fix it though.
>
