Re: [PATCH] cramfs: fix MTD dependency

[Nicolas Pitre]

On Wed, 15 Nov 2017, Arnd Bergmann wrote:

> On Fri, Nov 10, 2017 at 6:01 PM, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:
> > On Fri, 10 Nov 2017, Arnd Bergmann wrote:
> >
> >> On Fri, Nov 10, 2017 at 5:35 PM, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:
> >> > On Fri, 10 Nov 2017, Arnd Bergmann wrote:
> >> >
> >> >> With CONFIG_MTD=m and CONFIG_CRAMFS=y, we now get a link failure:
> >> >>
> >> >> fs/cramfs/inode.o: In function `cramfs_mount':
> >> >> inode.c:(.text+0x220): undefined reference to `mount_mtd'
> >> >> fs/cramfs/inode.o: In function `cramfs_mtd_fill_super':
> >> >> inode.c:(.text+0x6d8): undefined reference to `mtd_point'
> >> >> inode.c:(.text+0xae4): undefined reference to `mtd_unpoint'
> >> >>
> >> >> This adds a more specific Kconfig dependency to avoid the
> >> >> broken configuration. Alternatively we could make CRAMFS
> >> >> itself depend on "MTD || !MTD" with a similar result.
> >> >>
> >> >> Fixes: 99c18ce580c6 ("cramfs: direct memory access support")
> >> >> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> >> >> ---
> >> >>  fs/cramfs/Kconfig | 1 +
> >> >>  1 file changed, 1 insertion(+)
> >> >>
> >> >> diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig
> >> >> index f937082f3244..58e2fe40b2a0 100644
> >> >> --- a/fs/cramfs/Kconfig
> >> >> +++ b/fs/cramfs/Kconfig
> >> >> @@ -34,6 +34,7 @@ config CRAMFS_BLOCKDEV
> >> >>  config CRAMFS_MTD
> >> >>       bool "Support CramFs image directly mapped in physical memory"
> >> >>       depends on CRAMFS && MTD
> >> >> +     depends on CRAMFS=m || MTD=y
> >> >
> >> > I think the following is better:
> >> >
> >> > diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig
> >> > index f937082f32..a00740c668 100644
> >> > --- a/fs/cramfs/Kconfig
> >> > +++ b/fs/cramfs/Kconfig
> >> > @@ -33,7 +33,7 @@ config CRAMFS_BLOCKDEV
> >> >
> >> >  config CRAMFS_MTD
> >> >         bool "Support CramFs image directly mapped in physical memory"
> >> > -       depends on CRAMFS && MTD
> >> > +       depends on CRAMFS && (CRAMFS <= MTD)
> >> >         default y if !CRAMFS_BLOCKDEV
> >> >         help
> >> >           This option allows the CramFs driver to load data directly from
> >>
> >> I've never seen that syntax, what does it mean?
> >
> > In the Kconfig language: n < m < y. Therefore (m < y) is true and
> > (y < m) is false.
> 
> I see. However, since I didn't recognize that syntax, and it doesn't seem
> to be used much, I would still prefer my original suggestion, which
> I think is more common.

How can a "better" way become common enough for you to use it if you 
don't contribute to make it more common?


Nicolas