2.6 and the user-space ABI [LWN.net]

2.6 and the user-space ABI

Posted May 17, 2007 9:29 UTC (Thu) by sdalley (subscriber, #18550)
Parent article: 2.6 and the user-space ABI

What we surely need is a userspace kernel-lib that is part of the kernel tree and released as a matter of routine with each kernel update. The current udev and alsa libraries could go in there.

Then also, whenever a sysfs interface had to change, would be the time to step back and ask "what would an *application* need to see of this service?" (lm_sensors or whatever) and add the new higher-level hindsight-improved interface to kernel-ulib, or whatever it ends up being called. Move the sysfs interface for that service from "provisional" to "deprecated".

We could then buy ourselves flexibility without sacrificing quality.

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a userspace kernel-lib that is part of the kernel tree

Posted May 18, 2007 8:21 UTC (Fri) by xoddam (subscriber, #2322) [Link]

Yes yes yes yes yes.

Hear hear.

I agree with the above post.

What (s)he said.

2.6 and the user-space ABI

Posted May 18, 2007 12:55 UTC (Fri) by michaeljt (subscriber, #39183) [Link]

An intermediary solution would be to strongly suggest that people who need to access kernel ABIs from user space applications should look for existing libraries to do this and only do it through those libraries. If no suitable libraries were found, the functionality could be split off into a new library which could be published separately from the application, so that other applications could use that. That would limit the number of places where ABI changes would need to be fixed. Someone could even keep a database of known libraries which accessed the kernel ABI directly. Note that even syscalls are almost always accessed through libc.

2.6 and the user-space ABI

Posted May 21, 2007 3:19 UTC (Mon) by pimlott (guest, #1535) [Link]

Wait--that would be admitting that the filesystem isn't the single best interface for everything (the rationale for sysfs in the first place)! Heresy!

2.6 and the user-space ABI

Posted May 26, 2007 15:08 UTC (Sat) by anton (guest, #25547) [Link]

Yes. However, the number of incompatible changes could be reduced even more by out-of-kernel-tree stuff never accessing sysfs directly, but always through the kernel-lib. If such an application want something that is available through sysfs, but not the kernel-lib, then one could add an appropriate ABI to the kernel-lib, and that ABI is probably easier to keep stable than sysfs.