From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH] console: Add console=auto option Date: Thu, 16 Aug 2018 11:28:24 -0400 Message-ID: <4335912e-dab7-c516-d71e-47ed479c638a@redhat.com> References: <20180816141055.451-1-prarit@redhat.com> <20180816150948.GA10648@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180816150948.GA10648@kroah.com> Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Mark Salter , Al Stone , "Rafael J. Wysocki" , Len Brown , Pavel Machek , x86@kernel.org, Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Kees Cook , linux-pm@vger.kernel.org List-Id: linux-pm@vger.kernel.org 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 >> Cc: Mark Salter >> Cc: Al Stone >> Cc: "Rafael J. Wysocki" >> Cc: Len Brown >> Cc: Pavel Machek >> Cc: x86@kernel.org >> Cc: Petr Mladek >> Cc: Sergey Senozhatsky >> Cc: Steven Rostedt >> Cc: Kees Cook >> Cc: Greg Kroah-Hartman >> Cc: linux-pm@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 Use the hypervisor console device . 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); >> +} > > > >> +int arch_console_setup(void); > > Function does not match its prototype :( > > How did you build this successfully? Weird, it compiles on my system? I'll fix it though. P. >