ubifs: fix kconfig dependency warning

From: Randy Dunlap <randy.dunlap@oracle.com>

Fix another kconfig dependency warning, this time in ubifs.

warning: (UBIFS_FS_DEBUG && LOCKDEP && LATENCYTOP) selects KALLSYMS_ALL which has unmet direct dependencies (DEBUG_KERNEL && KALLSYMS)

Without this patch, we can have:
# CONFIG_KALLSYMS is not set
CONFIG_KALLSYMS_ALL=y
which is useless (does nothing unless KALLSYMS is enabled).

However, ubifs builds successfully with or without this patch,
and it builds with this line completely deleted,
so what was this 'select' for?  Just developer convenience?

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc:      Artem Bityutskiy <dedekind1@gmail.com>
Cc:      Adrian Hunter <adrian.hunter@nokia.com>
Cc:      linux-mtd@lists.infradead.org
---
 fs/ubifs/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On Mon, 2011-03-28 at 13:40 -0700, Randy Dunlap wrote:
> From: Randy Dunlap <randy.dunlap@oracle.com>
> 
> Fix another kconfig dependency warning, this time in ubifs.
> 
> warning: (UBIFS_FS_DEBUG && LOCKDEP && LATENCYTOP) selects KALLSYMS_ALL which has unmet direct dependencies (DEBUG_KERNEL && KALLSYMS)
> 
> Without this patch, we can have:
> # CONFIG_KALLSYMS is not set
> CONFIG_KALLSYMS_ALL=y
> which is useless (does nothing unless KALLSYMS is enabled).
> 
> However, ubifs builds successfully with or without this patch,
> and it builds with this line completely deleted,
> so what was this 'select' for?  Just developer convenience?

Well, here is the idea. You can compile UBIFS with debugging and without
debugging. Without debugging the resulting ubifs.ko is much smaller, so
some embedded people prefer it this way.

If you select debugging support, then we'll compile it a lot of
assertions, self-checks, test-modes, extra error messages with detailed
dumps. And we want to see stackdumps when errors or problems happen,
this is why we select KALLSYMS_ALL.

So I guess instead we should do:

select KALLSYMS
select KALLSYMS_ALL

?

On 03/29/11 00:02, Artem Bityutskiy wrote:
> On Mon, 2011-03-28 at 13:40 -0700, Randy Dunlap wrote:
>> From: Randy Dunlap <randy.dunlap@oracle.com>
>>
>> Fix another kconfig dependency warning, this time in ubifs.
>>
>> warning: (UBIFS_FS_DEBUG && LOCKDEP && LATENCYTOP) selects KALLSYMS_ALL which has unmet direct dependencies (DEBUG_KERNEL && KALLSYMS)
>>
>> Without this patch, we can have:
>> # CONFIG_KALLSYMS is not set
>> CONFIG_KALLSYMS_ALL=y
>> which is useless (does nothing unless KALLSYMS is enabled).
>>
>> However, ubifs builds successfully with or without this patch,
>> and it builds with this line completely deleted,
>> so what was this 'select' for?  Just developer convenience?
> 
> Well, here is the idea. You can compile UBIFS with debugging and without
> debugging. Without debugging the resulting ubifs.ko is much smaller, so
> some embedded people prefer it this way.
> 
> If you select debugging support, then we'll compile it a lot of
> assertions, self-checks, test-modes, extra error messages with detailed
> dumps. And we want to see stackdumps when errors or problems happen,
> this is why we select KALLSYMS_ALL.
> 
> So I guess instead we should do:
> 
> select KALLSYMS
> select KALLSYMS_ALL

Yes, that should do it.  Thanks for the explanation.

On Tue, 2011-03-29 at 08:01 -0700, Randy Dunlap wrote:
> On 03/29/11 00:02, Artem Bityutskiy wrote:
> > On Mon, 2011-03-28 at 13:40 -0700, Randy Dunlap wrote:
> >> From: Randy Dunlap <randy.dunlap@oracle.com>
> >>
> >> Fix another kconfig dependency warning, this time in ubifs.
> >>
> >> warning: (UBIFS_FS_DEBUG && LOCKDEP && LATENCYTOP) selects KALLSYMS_ALL which has unmet direct dependencies (DEBUG_KERNEL && KALLSYMS)
> >>
> >> Without this patch, we can have:
> >> # CONFIG_KALLSYMS is not set
> >> CONFIG_KALLSYMS_ALL=y
> >> which is useless (does nothing unless KALLSYMS is enabled).
> >>
> >> However, ubifs builds successfully with or without this patch,
> >> and it builds with this line completely deleted,
> >> so what was this 'select' for?  Just developer convenience?
> > 
> > Well, here is the idea. You can compile UBIFS with debugging and without
> > debugging. Without debugging the resulting ubifs.ko is much smaller, so
> > some embedded people prefer it this way.
> > 
> > If you select debugging support, then we'll compile it a lot of
> > assertions, self-checks, test-modes, extra error messages with detailed
> > dumps. And we want to see stackdumps when errors or problems happen,
> > this is why we select KALLSYMS_ALL.
> > 
> > So I guess instead we should do:
> > 
> > select KALLSYMS
> > select KALLSYMS_ALL
> 
> Yes, that should do it.  Thanks for the explanation.

Will you submit a patch? Alternatively, I can make it myself. What is
your preference?

And I'll merge it upstream this cycle (before 2.6.39) then.