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

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 12/06/18 01:50, Stefano Stabellini wrote:
> 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
Well I suggested a way during one of our recent chat and I am a bit 
surprised this was not considered here.
For reminder, the way was to provide a makefile target that will select 
tiny and the platform at the same time.
make tiny_defconfig PLAT=qemu

Cheers,

> > > 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
--
Julien Grall

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