From e52eec13cd6b7f30ab19081b387813e03e592ae5 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 8 Sep 2010 16:54:17 +0200 Subject: SYSFS: Allow boot time switching between deprecated and modern sysfs layout I have some systems which need legacy sysfs due to old tools that are making assumptions that a directory can never be a symlink to another directory, and it's a big hazzle to compile separate kernels for them. This patch turns CONFIG_SYSFS_DEPRECATED into a run time option that can be switched on/off the kernel command line. This way the same binary can be used in both cases with just a option on the command line. The old CONFIG_SYSFS_DEPRECATED_V2 option is still there to set the default. I kept the weird name to not break existing config files. Also the compat code can be still completely disabled by undefining CONFIG_SYSFS_DEPRECATED_SWITCH -- just the optimizer takes care of this now instead of lots of ifdefs. This makes the code look nicer. v2: This is an updated version on top of Kay's patch to only handle the block devices. I tested it on my old systems and that seems to work. Cc: axboe@kernel.dk Signed-off-by: Andi Kleen Cc: Kay Sievers Signed-off-by: Greg Kroah-Hartman --- init/Kconfig | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index 137609f..d742b6f 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -660,8 +660,12 @@ config SYSFS_DEPRECATED depends on SYSFS default n help - This option switches the layout of the "block" class devices, to not - show up in /sys/class/block/, but only in /sys/block/. + This option adds code that switches the layout of the "block" class + devices, to not show up in /sys/class/block/, but only in + /sys/block/. + + This switch is only active when the sysfs.deprecated=1 boot option is + passed or the SYSFS_DEPRECATED_V2 option is set. This option allows new kernels to run on old distributions and tools, which might get confused by /sys/class/block/. Since 2007/2008 all @@ -672,8 +676,22 @@ config SYSFS_DEPRECATED option enabled. Only if you are using a new kernel on an old distribution, you might - need to say Y here. Never say Y, if the original kernel, that came - with your distribution, has not set this option. + need to say Y here. + +config SYSFS_DEPRECATED_V2 + bool "enabled deprecated sysfs features by default" + default n + depends on SYSFS + depends on SYSFS_DEPRECATED + help + Enable deprecated sysfs by default. + + See the CONFIG_SYSFS_DEPRECATED option for more details about this + option. + + Only if you are using a new kernel on an old distribution, you might + need to say Y here. Even then, odds are you would not need it + enabled, you can always pass the boot option if absolutely necessary. config RELAY bool "Kernel->user space relay support (formerly relayfs)" -- cgit v1.1