Documentation: admin-guide: add earlycon documentation for RISC-V
diff mbox series

Message ID alpine.DEB.2.21.9999.1910091252160.11044@viisi.sifive.com
State New, archived
Headers show
Series
  • Documentation: admin-guide: add earlycon documentation for RISC-V
Related show

Commit Message

Paul Walmsley Oct. 9, 2019, 7:53 p.m. UTC
Kernels booting on RISC-V can specify "earlycon" with no options on
the Linux command line, and the generic DT earlycon support will query
the "chosen/stdout-path" property (if present) to determine which
early console device to use.  Document this appropriately in the
admin-guide.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andreas Schwab <schwab@suse.de>
---
 Documentation/admin-guide/kernel-parameters.txt | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Geert Uytterhoeven Oct. 10, 2019, 7:10 a.m. UTC | #1
On Wed, Oct 9, 2019 at 9:53 PM Paul Walmsley <paul.walmsley@sifive.com> wrote:
> Kernels booting on RISC-V can specify "earlycon" with no options on
> the Linux command line, and the generic DT earlycon support will query
> the "chosen/stdout-path" property (if present) to determine which
> early console device to use.  Document this appropriately in the
> admin-guide.
>
> Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert
Jonathan Corbet Oct. 10, 2019, 5:23 p.m. UTC | #2
On Thu, 10 Oct 2019 09:10:18 +0200
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> On Wed, Oct 9, 2019 at 9:53 PM Paul Walmsley <paul.walmsley@sifive.com> wrote:
> > Kernels booting on RISC-V can specify "earlycon" with no options on
> > the Linux command line, and the generic DT earlycon support will query
> > the "chosen/stdout-path" property (if present) to determine which
> > early console device to use.  Document this appropriately in the
> > admin-guide.
> >
> > Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>  
> 
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Applied, thanks.

jon
Christoph Hellwig Oct. 17, 2019, 4:10 p.m. UTC | #3
On Wed, Oct 09, 2019 at 12:53:50PM -0700, Paul Walmsley wrote:
> 
> Kernels booting on RISC-V can specify "earlycon" with no options on
> the Linux command line, and the generic DT earlycon support will query
> the "chosen/stdout-path" property (if present) to determine which
> early console device to use.  Document this appropriately in the
> admin-guide.

Jon already applied a patch from me removing the bogus arch restrictions
on the earlycon without arguments documentation, so this should not
be required.
Christoph Hellwig Nov. 8, 2019, 6:10 a.m. UTC | #4
Jon,

can you please revert this?  The paragraph above this addition already
describes the riscv case perfecty well with my previous patch:


	earlycon=	[KNL] Output early console device and options.

			When used with no options, the early console is
			determined by stdout-path property in device tree's
			chosen node or the ACPI SPCR table if supported by
			the platform.

			[RISCV] When used with no options, the early
			console is determined by the stdout-path
			property in the device tree's chosen node.
Paul Walmsley Nov. 11, 2019, 5:30 p.m. UTC | #5
Hi Jon,

On Fri, 8 Nov 2019, Christoph Hellwig wrote:

> can you please revert this?  The paragraph above this addition already
> describes the riscv case perfecty well with my previous patch:
> 
> 	earlycon=	[KNL] Output early console device and options.
> 
> 			When used with no options, the early console is
> 			determined by stdout-path property in device tree's
> 			chosen node or the ACPI SPCR table if supported by
> 			the platform.
> 
> 			[RISCV] When used with no options, the early
> 			console is determined by the stdout-path
> 			property in the device tree's chosen node.

I support reverting the RISCV section, now that Christoph's more general 
change has gone in.



- Paul
Jonathan Corbet Nov. 12, 2019, 4:44 p.m. UTC | #6
On Mon, 11 Nov 2019 17:30:13 +0000 (UTC)
Paul Walmsley <paul@pwsan.com> wrote:

> On Fri, 8 Nov 2019, Christoph Hellwig wrote:
> 
> > can you please revert this?  The paragraph above this addition already
> > describes the riscv case perfecty well with my previous patch:
> > 
> > 	earlycon=	[KNL] Output early console device and options.
> > 
> > 			When used with no options, the early console is
> > 			determined by stdout-path property in device tree's
> > 			chosen node or the ACPI SPCR table if supported by
> > 			the platform.
> > 
> > 			[RISCV] When used with no options, the early
> > 			console is determined by the stdout-path
> > 			property in the device tree's chosen node.  
> 
> I support reverting the RISCV section, now that Christoph's more general 
> change has gone in.

OK, the patch has been reverted.

Thanks,

jon

Patch
diff mbox series

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c7ac2f3ac99f..011fee969ece 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -990,6 +990,10 @@ 
 			[X86] When used with no options the early console is
 			determined by the ACPI SPCR table.
 
+			[RISCV] When used with no options, the early
+			console is determined by the stdout-path
+			property in the device tree's chosen node.
+
 		cdns,<addr>[,options]
 			Start an early, polled-mode console on a Cadence
 			(xuartps) serial port at the specified address. Only