On 7/28/13 11:57 PM, Keith Keller wrote: > On 2013-07-29, Eric Sandeen <sandeen@xxxxxxxxxxx> wrote: >> >> In general, no. There are a lot of moving parts that interface with >> the filesystem - one does not simply drop fs/xfs from, say, kernel >> 3.2 into a 2.6.32 kernel. > > I apologize for the confusion, this was not what I was implying was > possible. Let me try to be more explicit. Unfortunately, I no longer > have a history of what I did, because I ultimately abandoned it, so my > example will be hypothetical. > > The current stable kernel is 3.10.4. Let's suppose that 3.10.5 comes > out tomorrow with some interesting patches to fs/xfs. Is it possible > using dkms to build the 3.10.5 version of the xfs module for a running > 3.10.4 kernel? "Probably / Maybe" It really depends on what changed from 3.10.4 to 3.10.5, but odds are, kernel interfaces did not change, so - probably fine. If not, you get to keep all the pieces, etc. > And if so, is there a way for the module to report its > own version? Say it with me: there is no xfs module version. :) The "module version" is inherited from the kernel it's built against. $ modinfo xfs ... vermagic: 2.6.32-279.22.1.el6.x86_64 SMP mod_unload modversions > There should (in theory) be much less wizardry involved in > this scenario than in the difficult scenario of porting 3.10's xfs back > to 2.6, and is more along the lines of what I remember doing a short > time back). (To be specific, IIRC what I did was took a proposed patch > against my running kernel version, which had not yet been incorporated > in the distro kernel, and tested it by replacing the distro kernel's > module with one I built via DKMS. But as I mentioned, I have no docs on > this, so I could be misremembering the process.) Yeah, short version hops are more likely to be ok. And taking kernel version X's xfs, and applying a bugfix patch, and rebuilding it against the same kernel headers should be fine. Still a little wizardry, but not bad for a kernel-savvy person. > I am not intentionally trying to be difficult. :) I am genuinely > just curious about the answer. If it's "no" (or perhaps, in this > specific scenario, it's "use the dkms tools"), it still provides me with > valuable information I did not previously have. Sure, I don't think you're being difficult. The further you go off the reservation, the less tested things are, and the less likely they are to work. Building a tweaked, same-era module against a slightly different kernel is likely to be fine; it's when you get more & more changed / moving parts that it becomes trickier. But you need to know enough to know what you're changing and/or what has changed in the kernel, to know if what you're doing is completely safe, probably safe, or unlikely to be safe... -Eric > --keith > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
