Messages in this thread | | | Date | Fri, 17 Aug 2018 19:50:46 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH v2] console: Add console=auto option |
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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
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