Messages in this thread | | | Date | Wed, 25 Jun 2003 19:19:49 +0100 | From | Christoph Hellwig <> | Subject | Re: [RFC][PATCH] nbd driver for 2.5+: fix locking issues with ioctl UI |
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On Wed, Jun 25, 2003 at 12:16:10PM -0600, Lou Langholtz wrote: > >Hey, I didn't say changing the interface is wrong. But if possible > >do it in a way that the new userspace can still support the old kernel > >driver. > > > Agreed! Will do, but how???
if (detected_new_driver) { new_code(); } else { old_code(); }
in the userland app. if structures change in an incompatible way you need _v1 and _v2 versions of them of course.
And what to use for detected_new_driver? Probably the new ABI version ioctl..
> Cool! I'll take a look at these. Is this the prefered way then? There's > probably a lot of need for this generally speaking.
Yeah. And please do like device-mapper with major and minor versions. major as in completly incompatible and minor as in support old protocol but has new featues in addition.
> Thought about using > /proc for this too.
Bad idea :)
> And then sysfs is gaining favor so maybe in there?
Doesn't sound like a fit either. Maybe you could do a small own fs to control nbd, but I'm not familar enough with the actual API to comment on this more.
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