Andrew Morton <[EMAIL PROTECTED]> writes: > I note that the networking tree is adding new sysctls: > > <<<<<<< HEAD/include/linux/sysctl.h > NET_IPV6_ACCEPT_SOURCE_ROUTE=25, > ======= > NET_IPV6_OPTIMISTIC_DAD=24, > NET_IPV6_ACCEPT_SOURCE_ROUTE=25, >>>>>>>> /include/linux/sysctl.h > > (Well, it's trying to - there are some git rejects in net-2.6.22) > > But we kind-of decided a while back to stop doing that and to > use CTL_UNNUMBERED. > > Frankly, I don't 100% remember the thinking - Eric, can you please remind > us?
The thinking is this: Binary sysctl numbers are a problem because of patch conflicts like the above, and the related user space breakage they cause. In practice no one uses binary sysctl numbers. So the policy should be to add new sysctl's using CTL_UNNUMBERED (to prevent patch conflicts and user space breakage). There may be cases where someone actually needs the binary sysctl interface. Once there is a demonstrated need we can go back and very carefully add numbers for these very few cases, with a strong review process. Adding binary sysctl numbers should be done as carefully as and with as much review as adding syscall numbers, and distro kernels and other stable kernels should never get a sysctl number backport until the number first reaches Linus's tree. To avoid difference in meaning between different kernels. Given that no one except on BSD uses the binary sysctl interface anyway my personal preference is to just freeze it and to reduce the number of binary sysctls we support if possible. Eric - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
