[PATCH] documentation: make it clear that sysfs is optional

[PATCH] documentation: make it clear that sysfs is optional

[Randy Dunlap]

From:	Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
Subject: [PATCH] documentation: make it clear that sysfs is optional

The original text suggested that sysfs is mandatory and always
compiled in the kernel.

Signed-off-by: Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
---
 Documentation/filesystems/sysfs.txt |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- linux-next-20090727.orig/Documentation/filesystems/sysfs.txt
+++ linux-next-20090727/Documentation/filesystems/sysfs.txt
@@ -23,7 +23,8 @@ interface. 
 Using sysfs
 ~~~~~~~~~~~
 
-sysfs is always compiled in. You can access it by doing:
+sysfs is always compiled in if CONFIG_SYSFS is defined. You can access
+it by doing:
 
     mount -t sysfs sysfs /sys 
 


---
~Randy
LPC 2009, Sept. 23-25, Portland, Oregon
http://linuxplumbersconf.org/2009/

Re: [PATCH] documentation: make it clear that sysfs is optional

[Greg KH]

On Mon, Jul 27, 2009 at 09:06:42AM -0700, Randy Dunlap wrote:
> From:	Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
> Subject: [PATCH] documentation: make it clear that sysfs is optional
> 
> The original text suggested that sysfs is mandatory and always
> compiled in the kernel.

But it should be :)

Seriously, who turns sysfs off these days, does anyone?  If so, why?

thanks,

greg k-h

Re: [PATCH] documentation: make it clear that sysfs is optional

[Randy Dunlap]

On Mon, 27 Jul 2009 09:10:33 -0700 Greg KH wrote:

> On Mon, Jul 27, 2009 at 09:06:42AM -0700, Randy Dunlap wrote:
> > From:	Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
> > Subject: [PATCH] documentation: make it clear that sysfs is optional
> > 
> > The original text suggested that sysfs is mandatory and always
> > compiled in the kernel.
> 
> But it should be :)

Well, you have the option of making it non-optional.


> Seriously, who turns sysfs off these days, does anyone?  If so, why?

Why is it configurable then?


---
~Randy
LPC 2009, Sept. 23-25, Portland, Oregon
http://linuxplumbersconf.org/2009/

Re: [PATCH] documentation: make it clear that sysfs is optional

[Greg KH]

On Mon, Jul 27, 2009 at 09:18:24AM -0700, Randy Dunlap wrote:
> On Mon, 27 Jul 2009 09:10:33 -0700 Greg KH wrote:
> 
> > On Mon, Jul 27, 2009 at 09:06:42AM -0700, Randy Dunlap wrote:
> > > From:	Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
> > > Subject: [PATCH] documentation: make it clear that sysfs is optional
> > > 
> > > The original text suggested that sysfs is mandatory and always
> > > compiled in the kernel.
> > 
> > But it should be :)
> 
> Well, you have the option of making it non-optional.
> 
> 
> > Seriously, who turns sysfs off these days, does anyone?  If so, why?
> 
> Why is it configurable then?

Probably the same reason /proc is configurable.  No one ever turns it
off, but hey, it's possible :)

thanks,

greg k-h

Re: [PATCH] documentation: make it clear that sysfs is optional

[Henrique de Moraes Holschuh]

On Mon, 27 Jul 2009, Greg KH wrote:
> On Mon, Jul 27, 2009 at 09:18:24AM -0700, Randy Dunlap wrote:
> > On Mon, 27 Jul 2009 09:10:33 -0700 Greg KH wrote:
> > > On Mon, Jul 27, 2009 at 09:06:42AM -0700, Randy Dunlap wrote:
> > > > The original text suggested that sysfs is mandatory and always
> > > > compiled in the kernel.
> > > 
> > > But it should be :)
> > 
> > Well, you have the option of making it non-optional.
> > 
> > > Seriously, who turns sysfs off these days, does anyone?  If so, why?
> > 
> > Why is it configurable then?
> 
> Probably the same reason /proc is configurable.  No one ever turns it
> off, but hey, it's possible :)

But does anyone ever test if the system doesn't go to lunch when you do
that?

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: [PATCH] documentation: make it clear that sysfs is optional

[Greg KH]

On Mon, Jul 27, 2009 at 07:49:30PM -0300, Henrique de Moraes Holschuh wrote:
> On Mon, 27 Jul 2009, Greg KH wrote:
> > On Mon, Jul 27, 2009 at 09:18:24AM -0700, Randy Dunlap wrote:
> > > On Mon, 27 Jul 2009 09:10:33 -0700 Greg KH wrote:
> > > > On Mon, Jul 27, 2009 at 09:06:42AM -0700, Randy Dunlap wrote:
> > > > > The original text suggested that sysfs is mandatory and always
> > > > > compiled in the kernel.
> > > > 
> > > > But it should be :)
> > > 
> > > Well, you have the option of making it non-optional.
> > > 
> > > > Seriously, who turns sysfs off these days, does anyone?  If so, why?
> > > 
> > > Why is it configurable then?
> > 
> > Probably the same reason /proc is configurable.  No one ever turns it
> > off, but hey, it's possible :)
> 
> But does anyone ever test if the system doesn't go to lunch when you do
> that?

I have no idea, I doubt it...

Re: [PATCH] documentation: make it clear that sysfs is optional

[Christian Kujau]

On Mon, 27 Jul 2009 at 09:26, Greg KH wrote:
> Probably the same reason /proc is configurable.  No one ever turns it
> off, but hey, it's possible :)

Hm, it seems as we cannot turn off PROC_FS or SYSFS any more. At least on 
my system a "make allnoconfig" still selects both. While PROC_FS still 
shows up under Filesystems->Pseudo-Filesystem (but cannot be turned off), 
I don't see a menuconfig knob to turn off SYSFS.
However, "make allnoconfig" still selects quite a few options anyway:

# uname -m
x86_64
# make allnoconfig
# grep -c =y .config
175

(manually editing .config gets reverted on another "make config").

So, it loks like SYSFS is just one of the things needed to build a kernel, 
along with the ~170 other things, at least on x86_64. Is this "make it 
clear that sysfs is optional" patch still valid? :-)

Christian.

sid$ find . -name Kconfig | xargs grep SYSFS  | egrep -v 'drivers/|fs/|net/'
./arch/arm/mach-pxa/Kconfig:    select GPIO_SYSFS
./arch/powerpc/kvm/Kconfig:     depends on KVM && MARKERS && SYSFS
./arch/x86/kvm/Kconfig: depends on KVM && SYSFS
./init/Kconfig:config SYSFS_DEPRECATED
./init/Kconfig:config SYSFS_DEPRECATED_V2
./init/Kconfig: depends on SYSFS
./init/Kconfig: select SYSFS_DEPRECATED
./init/Kconfig: depends on SLUB && SYSFS
./kernel/trace/Kconfig: depends on SYSFS
./security/Kconfig:     depends on SYSFS


-- 
BOFH excuse #228:

That function is not currently supported, but Bill Gates assures us it will be featured in the next upgrade.

Re: [PATCH] documentation: make it clear that sysfs is optional

[Randy Dunlap]

On Sat, 1 Aug 2009 02:14:47 -0700 (PDT) Christian Kujau wrote:

> On Mon, 27 Jul 2009 at 09:26, Greg KH wrote:
> > Probably the same reason /proc is configurable.  No one ever turns it
> > off, but hey, it's possible :)
> 
> Hm, it seems as we cannot turn off PROC_FS or SYSFS any more. At least on 
> my system a "make allnoconfig" still selects both. While PROC_FS still 
> shows up under Filesystems->Pseudo-Filesystem (but cannot be turned off), 
> I don't see a menuconfig knob to turn off SYSFS.
> However, "make allnoconfig" still selects quite a few options anyway:
> 
> # uname -m
> x86_64
> # make allnoconfig
> # grep -c =y .config
> 175
> 
> (manually editing .config gets reverted on another "make config").
> 
> So, it loks like SYSFS is just one of the things needed to build a kernel, 
> along with the ~170 other things, at least on x86_64. Is this "make it 
> clear that sysfs is optional" patch still valid? :-)


It's no problem to disable PROC_FS and SYSFS if you first enable
CONFIG_EMBEDDED>


> sid$ find . -name Kconfig | xargs grep SYSFS  | egrep -v 'drivers/|fs/|net/'
> ./arch/arm/mach-pxa/Kconfig:    select GPIO_SYSFS
> ./arch/powerpc/kvm/Kconfig:     depends on KVM && MARKERS && SYSFS
> ./arch/x86/kvm/Kconfig: depends on KVM && SYSFS
> ./init/Kconfig:config SYSFS_DEPRECATED
> ./init/Kconfig:config SYSFS_DEPRECATED_V2
> ./init/Kconfig: depends on SYSFS
> ./init/Kconfig: select SYSFS_DEPRECATED
> ./init/Kconfig: depends on SLUB && SYSFS
> ./kernel/trace/Kconfig: depends on SYSFS
> ./security/Kconfig:     depends on SYSFS


---
~Randy
LPC 2009, Sept. 23-25, Portland, Oregon
http://linuxplumbersconf.org/2009/