Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH v4 0/4] ACPI: parse the SPCR table | From | Aleksey Makarov <> | Date | Fri, 11 Mar 2016 23:25:13 +0700 |
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Hi Peter,
You are right, SPCR console should support earlycon. I will send next version that will try to follow your recommendations in a week, after I return from vacations.
As we discussed with Christopher, "serial: pl011: use SPCR to setup 32-bit access" will be dropped.
Thank you Aleksey Makarov
On 04.03.2016 22:47, Peter Hurley wrote: > On 03/04/2016 03:53 AM, Aleksey Makarov wrote: >> >> >> On 03/03/2016 06:35 PM, Peter Hurley wrote: >>> On 03/03/2016 03:59 AM, Aleksey Makarov wrote: >>>> >>>> >>>> On 03/01/2016 06:31 PM, Peter Hurley wrote: >>>>> On 02/29/2016 04:02 AM, Aleksey Makarov wrote: >>>>>> 'ARM Server Base Boot Requirements' [1] mentions SPCR (Serial Port >>>>>> Console Redirection Table) [2] as a mandatory ACPI table that >>>>>> specifies the configuration of serial console. >>>>>> >>>>>> Introduce a new function acpi_console_check(). At the uart port >>>>>> registration, this function checks if the ACPI SPCR table specifies >>>>>> its argument of type struct uart_port to be a console >>>>>> and if so calls add_preferred_console(). >>>>> >>>>> How will a user enable an earlycon on the same console as the SPCR >>>>> console if there is no DBG2 table? >>>> >>>> ... >>>> [ 0.000000] earlycon: pl11 at MMIO 0x0000000009000000 (options '') >>>> [ 0.000000] bootconsole [pl11] enabled >>>> ... >>>> [ 0.000000] Kernel command line: root=/dev/vda1 rw systemd.show_status=no acpi=force earlycon=pl011,0x9000000 >>>> ... >>>> [ 0.318248] ACPI: SPCR: adding preferred console [ttyAMA0] >>>> [ 0.318736] ARMH0011:00: ttyAMA0 at MMIO 0x9000000 (irq = 5, base_baud = 0) is a SBSA >>>> [ 0.319502] console [ttyAMA0] enabled >>>> [ 0.319502] console [ttyAMA0] enabled >>>> [ 0.319933] bootconsole [pl11] disabled >>>> [ 0.319933] bootconsole [pl11] disabled >>>> ... >>>> >>>> Why? >>> >>> That's pretty disingenuous; via command line? >>> >>> By that measure, none of your patches are required because a user >>> can already start both console and earlycon without them. >>> >>> With the console location specified in the SPCR, earlycon should >>> be opt-in on the command-line simply with "earlycon" command-line >>> parameter. >> >> Yes. That's why we have SPCR *and* DBG2. >> DBG2 specifies where we should run earlycon. >> >>>>> How will a user enable an earlycon on the same console as the SPCR >>>>> console if there is no DBG2 table? >> >> In no way. You need DBG2 to run earlycon. > > And that's an entirely arbitrary decision being made by you. > Which I think is unnecessarily limited. > > >> (If you don't want to specify it's address etc explicitly) > >
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