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) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
