Messages in this thread | | | From | Florian Fainelli <> | Subject | Re: [PATCH] TTY: export NR_LDISC and N_* line discipline numbers to user-space | Date | Tue, 24 May 2011 15:17:23 +0200 |
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Hello,
On Tuesday 24 May 2011 14:40:44 Greg KH wrote: > On Tue, May 24, 2011 at 10:43:03AM +0200, Florian Fainelli wrote: > > From: Florian Fainelli <ffainelli@freebox.fr> > > > > Since commit (4564f9e5: consolidate line discipline number definitions) > > the patch moved all line discipline number from a per-architecture > > termios.h to a shared one: tty.h. However, prior to this consolidation > > work, the line discipline numbers were outside of an ifdef > > __KERNEL__/endif block so these numbers used to be exported to > > user-space. > > > > Since such numbers are kernel ABI anyway, and tty.h is already included > > for user- space header processing, just move these relevant defines > > outside of the ifdef __KERNEL__/endif block in include/linux/tty.h. > > Any reason you didn't copy _any_ of the people who signed off on that > patch, or the original author of that patch?
No particular reason but my mistake, fixed that.
> > Anyway, this is been this way for four years, since the 2.6.21 kernel > release. Since no one has noticed, or complained, since then, how much > a problem is this really?
This is a problem because you may have out of tree drivers using a line discpline number, and you do not want your companion user-space application to have to use a different line discpline number but the one the kernel should provide.
> > Meaning, why has it taken this long for anyone to notice?
- long standing user-space applications such as pppd got their N_PPP long ago, and do not have to worry about N_PPP being renumbered so they can just define it in pppd's sources it won't break
- I started implementing a line discipline driver only a couple of months ago and then realized that such ABI should have been exported -- Florian
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