[RFC v8 19/20] um: lkl: add block device support of UML

[Johannes Berg]

On Tue, 2021-03-16 at 10:19 +0900, Hajime Tazaki wrote:
> 
> > > --- a/arch/um/Kconfig
> > > +++ b/arch/um/Kconfig
> > > @@ -29,6 +29,10 @@ config UMMODE_LIB
> > >  	select UACCESS_MEMCPY
> > >  	select ARCH_THREAD_STACK_ALLOCATOR
> > >  	select ARCH_HAS_SYSCALL_WRAPPER
> > > +	select VFAT_FS
> > > +	select NLS_CODEPAGE_437
> > > +	select NLS_ISO8859_1
> > > +	select BTRFS_FS
> > 
> > That doesn't really seem to make sense - the sample might need it, but
> > generally LKL doesn't/shouldn't?
> 
> I'm trying to understand your comment;
> Do you mean that enabling those options in Kconfig doesn't make sense ?

I mean *always* enabling them doesn't make sense. Why shouldn't somebody
be allowed to build UMMODE_LIB *without* btrfs? If they have no need for
btrfs, why should it select it?

I can understand that your sample code wants btrfs just to show what it
can do, but IMHO it doesn't make sense to *always* enable it.

> and if you mean the sample as sample code, is the added test case
> (e.g., tools/testing/selftests/um/disk.c, which is included in the
> same patch) for this purpose ?

yes, that's what I mean by "sample code"

joahnnes