From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel@vger.kernel.org, Mark Salter <msalter@redhat.com>,
Al Stone <ahs3@redhat.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
x86@kernel.org, Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Kees Cook <keescook@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-pm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v2] console: Add console=auto option
Date: Fri, 17 Aug 2018 19:50:46 +0900 [thread overview]
Message-ID: <20180817105046.GB10337@jagdpanzerIV> (raw)
In-Reply-To: <a530a430-70ce-c1e1-ccba-bf5df107c5ad@redhat.com>
Hello,
Cc-ing Peter Zijlstra
lkml.kernel.org/r/728a8e68-ea4b-4040-a0fc-217df4f1928d@redhat.com
lkml.kernel.org/r/20180817081947.m425gok2ugt7tglp@pathway.suse.cz
lkml.kernel.org/r/00c60dca-60bc-8568-eaa3-d4b0c326cab4@redhat.com
On (08/17/18 06:36), Prarit Bhargava wrote:
> On 08/17/2018 05:38 AM, Sergey Senozhatsky wrote:
> > On (08/16/18 13:39), Prarit Bhargava wrote:
> >>
> >> + auto [X86] Enable ACPI SPCR console
> > ^^^^
> > And arm64?
>
> Hi Sergey, on arm64 if an SPCR is present the early console and console are
> initialized by default. IOW no kernel parameter is necessary to initialize the
> console in that case.
OK, thanks.
> > Any chance we can rename param to "spcr" or something more clear?
> > To explicitly state what exactly it's going to do. `auto' sounds
> > too general and doesn't tell me that much. I'm probably the only
> > here who can't see a connection between "auto" and "SPCR", but
> > still.
>
> I came up with "auto" because I think it is generic. I also thought about
> "console=fw", or just "console". If in the future another arch wants to
> optionally bring up a firmware or hardware defined console then they could use
> auto too.
Hmm, I see your point.
My [sort of a] problem with "auto" is that it tells me as much as "magic"
[and "magic" tells me almost nothing]. By the way, would be fun if we had
"magic" instead of "auto" all over the kernel
echo "magic" > /sys/bus/usb/...../power/control
> > void arch_console_setup(void)
> > {
> > if (acpi_parse_spcr(false, true))
> > pr_err(.........);
> > }
> >
> > There can be other consoles in the system, logging an error is not
> > such a useless thing.
>
> I can make the second change. The problem (IIRC) with returning an error in an
> setup fn is that the rest of the setup functions will not execute. I don't want
> to fail the setup callbacks because of an incorrect SPCR table.
OK, fair enough.
Letting users know that SPCR is incorrect also makes sense, so option #2
I guess is what we want after all.
> Like I mentioned to Petr, I'd like to know if you (or anyone else) has strong
> feelings about changing the behaviour of earlycon on x86? I could make it so
> that specifying just earlycon would also initialize the console.
x86 people and/or scheduler people might have strong opinions on this.
I Cc-ed Peter Zijlstra; he represents both groups and is known to be
a hardcore earlycon user.
-ss
next prev parent reply other threads:[~2018-08-17 10:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-16 14:10 [PATCH] console: Add console=auto option Prarit Bhargava
2018-08-16 15:09 ` Greg Kroah-Hartman
2018-08-16 15:28 ` Prarit Bhargava
2018-08-16 15:33 ` Steven Rostedt
2018-08-16 17:23 ` Prarit Bhargava
2018-08-16 17:39 ` [PATCH v2] " Prarit Bhargava
2018-08-17 8:19 ` Petr Mladek
2018-08-17 10:26 ` Prarit Bhargava
2018-08-17 9:38 ` Sergey Senozhatsky
2018-08-17 10:36 ` Prarit Bhargava
2018-08-17 10:50 ` Sergey Senozhatsky [this message]
2018-08-17 11:06 ` Prarit Bhargava
2018-08-17 12:57 ` Petr Mladek
2018-08-29 12:54 ` Prarit Bhargava
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