Messages in this thread | | | Date | Mon, 10 Jul 2023 08:41:41 -0700 | Subject | Re: [PATCH] init: Don't proxy console= to earlycon | From | Randy Dunlap <> |
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Hi,
On 7/10/23 08:30, Raul Rangel wrote: > On Sun, Jul 9, 2023 at 8:43 PM Randy Dunlap <rdunlap@infradead.org> wrote: >> >> >> >> On 7/9/23 18:15, Mario Limonciello wrote: >>> On 7/9/23 18:46, Randy Dunlap wrote: >>>> >>>> >>>> On 7/7/23 18:17, Raul E Rangel wrote: >>>>> Right now we are proxying the `console=XXX` command line args to the >>>>> param_setup_earlycon. This is done because the following are >>>>> equivalent: >>>>> >>>>> console=uart[8250],mmio,<addr>[,options] >>>>> earlycon=uart[8250],mmio,<addr>[,options] >>>>> >>>>> In addition, when `earlycon=` or just `earlycon` is specified on the >>>>> command line, we look at the SPCR table or the DT to extract the device >>>>> options. >>>>> >>>>> When `console=` is specified on the command line, it's intention is to >>>>> disable the console. Right now since we are proxying the `console=` >>>> >>>> How do you figure this (its intention is to disable the console)? >>> > > https://www.kernel.org/doc/html/v6.1/admin-guide/kernel-parameters.html > says the following:
> console=
[many lines deleted here in kernel-parameters.txt]
> { null | "" } > Use to disable console output, i.e., to have kernel > console messages discarded. > This must be the only console= parameter used on the > kernel command line. >
OK, I see what you are referring to: "console=" without any following parameters, not the general "console=" command line parameter.
Thanks for the clarification.
> 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. > > The reason this bug showed up is that ChromeOS has set `console=` for a > very long time: > https://chromium.googlesource.com/chromiumos/platform/crosutils/+/main/build_kernel_image.sh#282 > I'm not sure on the exact history, but AFAIK, we don't have the ttyX devices. > > Coreboot recently added support for the ACPI SPCR table which in > combination with the > `console=` arg, we are now seeing earlycon enabled when it shouldn't be. > >>> I read that as "it's intention is to disable the default console (tty0)". >> >> Yes, that "default" word should be there IMO. >> >> Does this patch affect behavior if someone uses >> console=tty0 >> i.e., the default? >> > > No, it shouldn't. This change makes it so that the > param_setup_earlycon function gets > skipped if there is no value. > See https://chromium.googlesource.com/chromiumos/third_party/kernel/+/v6.1/drivers/tty/serial/earlycon.c#223
-- ~Randy
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