Re: [Xen-devel] [PATCH v5 07/10] arm: add a tiny kconfig configuration

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 5 Jun 2018, Julien Grall wrote:
> Hi Stefano,
> 
> On 04/06/18 18:24, Stefano Stabellini wrote:
> > Add a tiny kconfig configuration. Enabled NULL and Credit schedulers.
> > Support only 8 cpus. It only carries non-default options (use make
> 
> I don't see where 8 CPUs would only be supported as the default value is 128
> cpus.
 
I need to update the commit message reflecting the changes to the patch


> > olddefconfig to produce a complete .config file).
> 
> With all the series I did the following things:
>       1) copy tiny.config to .config
>       2) make olddefconfig
>       3) make menuconfig and select QEMU
> 
> After 1) the numbers of CPUs are set to 128. After 3) I would expect the
> number of CPUs to go down to 8. Unfortunately this is not the cases.
>
> So your command does not seem to be enough here.

NR_CPUS cannot go down. It is a limitation of Kconfig, similar to the
fact that option cannot be de-selected.

It is not 1) that sets NR_CPUS to 128, it would be 2) above. For this to
work you have to skip 2) and just do:

        - copy tiny.config to .config
        - make menuconfig and select QEMU


> > 
> > Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > 
> > ---
> > ---
> >   xen/arch/arm/configs/tiny.conf | 43
> > ++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 43 insertions(+)
> >   create mode 100644 xen/arch/arm/configs/tiny.conf
> > 
> > diff --git a/xen/arch/arm/configs/tiny.conf b/xen/arch/arm/configs/tiny.conf
> > new file mode 100644
> > index 0000000..e9a5e65
> > --- /dev/null
> > +++ b/xen/arch/arm/configs/tiny.conf
> > @@ -0,0 +1,43 @@
> > +CONFIG_ARM_64=y
> 
> This config targets arm64. So I would name it tiny64.conf.

OK


> > +CONFIG_ARM=y
> > +
> > +#
> > +# Architecture Features
> > +#
> > +# CONFIG_GICV3 is not set
> > +# CONFIG_MEM_ACCESS is not set
> > +# CONFIG_SBSA_VUART_CONSOLE is not set
> > +
> > +#
> > +# Common Features
> > +#
> > +# CONFIG_TMEM is not set
> > +
> > +#
> > +# Schedulers
> > +#
> > +# CONFIG_SCHED_CREDIT2 is not set
> > +# CONFIG_SCHED_RTDS is not set
> > +# CONFIG_SCHED_ARINC653 is not set
> > +CONFIG_SCHED_NULL=y
> > +CONFIG_SCHED_NULL_DEFAULT=y
> > +CONFIG_SCHED_DEFAULT="null"
> > +# CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS is not set
> > +
> > +#
> > +# Device Drivers
> > +#
> > +# CONFIG_HAS_NS16550 is not set
> > +# CONFIG_HAS_CADENCE_UART is not set
> > +# CONFIG_HAS_MVEBU is not set
> > +# CONFIG_HAS_PL011 is not set
> > +# CONFIG_HAS_SCIF is not set
> > +# CONFIG_ARM_SMMU is not set
> > +
> > +#
> > +# Debugging Options
> > +#
> > +# CONFIG_DEBUG is not set
> > +# CONFIG_FRAME_POINTER is not set
> > +# CONFIG_VERBOSE_DEBUG is not set
> > +# CONFIG_SCRUB_DEBUG is not set
> > 
> 
> Cheers,
> 
> -- 
> Julien Grall
> 

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