Re: [coreboot] Some v3 Kconfig options into dts?

[ron minnich]

On Wed, Oct 1, 2008 at 12:44 PM, Peter Stuge  wrote:
> [e-mail] wrote:
> > config K8_SCAN_PCI_BUS
> >   Whether to scan the PCI bus in stage1.

I adopted this from v2 but it would only be a mainboard issue; it
should never be in dts since it's not an option anyone should ever
set.
> > config K8_ALLOCATE_IO_RANGE
> >   Whether to allocate I/O space in stage1.
> >
> > config K8_ALLOCATE_MMIO_RANGE
> >   Whether to allocate MMIO space in stage1.

same.
> > config LOGICAL_CPUS
> >   How many logical CPUs there are. FIXME.

should always be determined dynamically by what cpus are installed.
> > config MAX_PHYSICAL_CPUS
> >   Maximum number of physical CPUs (sockets).
>
> dts?

This comes down to wires. I don't see it in the dts.
> > config MAX_PHYSICAL_CPUS_4_BUT_MORE_INSTALLED
> >   Config with 4 CPUs even if more are installed.
>
> But I think this should stay in Kconfig.

yes. It's a bizarre variable which I hope to remove some day.
> > config CROSS_BAR_47_56
> >   Configure for the type of crossbar on the mainboard.
>
> dts?

no. It's wires.
> >   help
> >     This option is used to determine whether the mainboard has
> >   a PIRQ table, which is the old way to set up interrupt routing.
> >   It is usually set in mainboard/*/Kconfig.
> >
> > config ACPI_TABLE
> >       boolean
> >       help
> >         This option is used to determine whether the mainboard has
> >   an ACPI table.
> >   It is usually set in mainboard/*/Kconfig.
>
> dts?

no. it's a build option.
> > config SMP
> >   depends CPU_I586 || CPU_AMD_K8
> >   default 0
> >   help
> >   This option is used to enable certain functions to make coreboot
> >   work correctly on symmetric multi processor systems.
> >   It is usually set in mainboard/*/Kconfig.
>
> Could this be derived from the number of logical CPUs?

Yes. this is not an OS, it's a BIOS, and SMP should always be enabled.
> > config IOAPIC
> > @@ -153,7 +152,7 @@
> >       depends ARCH_X86 && CPU_AMD_K8
> >       default 0
> >       help
> >   If you want to configure an IOAPIC, set this.
>
> Will the builder really have an opinion on this? Isn't it chip
> dependent? (ie -> dts?)

it's something they should never want to see or change. Not even dts.
> > config K8_HT_FREQ_1G_SUPPORT
> >   1 GHz support. Opteron E0 or later can support 1G HT,
> >   but still depends on the mainboard.
>
> dts?

no, it's a mainboard issue.
> > config HT_FREQ_800MHZ
> >   Can we run HT at 800 MHz.
>
> dts?

same.
> > config USBDEBUG_DIRECT
> >       depends SOUTHBRIDGE_NVIDIA_MCP55
>
> Chip specific and board specific so a chip dts setting that is
> filtered through the board dts and can make a Kconfig option visible
> that the builder can use to disabled USB debug output?

Here's the big issue. There are things that can be set in Kconfig AND
in dts; there are things that are settings that should not be in
Kconfig OR dts, because setting them could cause Bad Things To Happen.

For that latter type of variable, I just created mainboard.h. For the
Kconfig/dts issue, it's a judgement call. Possibly the best thing to
do is have the dts able to use Kconfig variables in some settings:
baud = "CONFIG_TTYS0_BAUD";
> > config APIC_ID_OFFSET
> >   This is entirely mainboard dependent.
>
> dts?

no, I don't ever want a person building a bios to think this is a
variable they should touch.

But it really gets down to the role of the dts. I think of it as
something people can change. Things that can never change don't belong
in dts or Kconfig I think.

ron