Re: how to handle indirect kconfig dependencies

[James Bottomley <James.Bottomley@SteelEye.com>]

On Thu, 2006-11-16 at 20:07 -0800, Randy Dunlap wrote:
> Hi,
> 
> I have a (randconfig) build of 2.6.19-rc5-mm2 with:
> 
> CONFIG_DEBUG_READAHEAD=y
> 
> which selects DEBUG_FS, so DEBUG_FS=y, but DEBUG_FS depends on
> SYSFS, and SYSFS is not set in the randconfig.
> 
> This randconfig causes this build error:
> 
> fs/built-in.o: In function `debugfs_init':
> inode.c:(.init.text+0xdb2): undefined reference to `kernel_subsys'
> 
> so the question is:
> (How) can kconfig follow the dependency chain and either
> - prevent this odd config combination or
> - see that 'select DEBUG_FS' implies 'select SYSFS' and then enable SYSFS
> ?
> 
> I don't believe that the right answer is to add
> 	depends on SYSFS
> to DEBUG_READAHEAD.
> 
> 
> .config is at http://oss.oracle.com/~rdunlap/configs/config-readahead-debugfs

Actually, no, I don't think this is the right thing to do.  If we can't
persuade selected CONFIG options to give an inherited dependency to the
selectee, then the only other option is to make sure that selectable
config options have no dependencies (i.e. they select everything they
need).

James