how to handle indirect kconfig dependencies

how to handle indirect kconfig dependencies

[Randy Dunlap]

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

Thanks,
---
~Randy [or just kill off select]

Re: how to handle indirect kconfig dependencies

[Stefan Richter]

Randy Dunlap wrote:
> I have a (randconfig) build of 2.6.19-rc5-mm2 with:
[...]
> 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.

I know this doesn't concludingly answer your question, but: All of the
various shipped tools to generate .config need to be fixed to recognize
"select" to imply a dependency like "depends on" does.

[...]
> ~Randy [or just kill off select]

Or this. ("select" appears to be useful for dialog driven creation of
.config in cases where developers are able to predetermine preferences
of users --- nothing more and nothing less.)
-- 
Stefan Richter
-=====-=-==- =-== =---=
http://arcgraph.de/sr/

Re: how to handle indirect kconfig dependencies

[Adrian Bunk]

On Fri, Nov 17, 2006 at 02:55:09PM +0100, Stefan Richter wrote:
> Randy Dunlap wrote:
> > I have a (randconfig) build of 2.6.19-rc5-mm2 with:
> [...]
> > 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.
> 
> I know this doesn't concludingly answer your question, but: All of the
> various shipped tools to generate .config need to be fixed to recognize
> "select" to imply a dependency like "depends on" does.
>...

BTW:
"All of the various shipped tools ... need to be fixed" is a bit 
misleading since one of the features of the 2.6 kconfig is that this 
code is shared by all tools.

> Stefan Richter

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: how to handle indirect kconfig dependencies

[Stefan Richter]

Adrian Bunk wrote:
> "All of the various shipped tools ... need to be fixed" is a bit 
> misleading since one of the features of the 2.6 kconfig is that this 
> code is shared by all tools.

All the better, the job will be quickly done then.
-- 
Stefan Richter
-=====-=-==- =-== =-=--
http://arcgraph.de/sr/

Re: how to handle indirect kconfig dependencies

[James Bottomley]

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

Re: how to handle indirect kconfig dependencies

[Randy Dunlap]

On Thu, 16 Nov 2006 20:07:41 -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

Roman,
Here's another one for your consideration.

USB_APPLEDISPLAY selects BACKLIGHT_LCD_SUPPORT & BACKLIGHT_CLASS_DEVICE;
drivers/backlight/Kconfig depends on SYSFS (but SYSFS=n)

http://oss.oracle.com/~rdunlap/configs/config-backlight-appledisplay

---
~Randy