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

[Julien Grall <julien.grall@xxxxxxx>]

On 12/06/2018 20:41, Stefano Stabellini wrote:
> On Tue, 12 Jun 2018, Julien Grall wrote:
> > Hi,
> >
> > On 12/06/18 16:55, Stefano Stabellini wrote:
> > > On Tue, 12 Jun 2018, Julien Grall wrote:
> > > > 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
> > > I prefer not to add additional targets
> > I think it would make easier for user to select any config and the platform.
> > It is one command over 3 that can mistakenly be misused.
> >
> > Anyway, sooner or later we will want to have such target in Xen.
> Feel like writing a small patch for it? I would be happy to include it
> :-)
I have a 12h flight on Friday, I might have a look to kill the time :).

Cheers,

>

--
Julien Grall

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