On 14.03.2014 17:51, Christos Zoulas wrote: > On Mar 14, 5:29pm, net...@izyk.ru (Ilya Zykov) wrote: > -- Subject: Re: Enhance ptyfs to handle multiple instances. > > | Ok. > | > | 1. The main problem and question in this project(IMHO), it's how get access > for every instance through one driver ptm[x]. > | First version. > | We can do it as well "Linux devpts" do. Inside every ptyfs we can create > not only slave side files, > | but ptm[x] too for this instance. But who must create(kernel mount function > or userspace helper) and what permissions will assign? > > We first need to decide if disclosing gaps in the pty number is a security > issue. If not, it is simple; we just allocate the next free one and we don't > care about gaps. I.e. first mount can grab 0,1,2,3,5,6 second mount can grab > 4,7,8 etc.
It introduces limits. >If we care, we can use an indirect mapping. I don't think that we > care. I don't think that putting ptmx inside devpts makes sense. We can easy differentiate ptyfs instance. >OTOH, we > could have multiple ptmx devices with different minor numbers and use that > as the differentiating factor for the pty devices. Sorry my tongue-tie, maybe you don't understand me correctly, but this is my (One more version). > I think that's too complex > and probably not worth it (at least in the first pass). > > | One more version. > | We can do many ptm[x] minor numbers(165:0 165:1 for first instance, 165:2 > 165:3 for second ...) this can be anywhere in fs. > | But then for every mount we must pass for what instance it's mount doing. > We can do it with new mount option "instance=#"(for example). > | Every version has advantages and disadvantage. I think first version more > clear. What do you think? > > I think that this is not very desirable because it again introduces limits > to the number of ptys per mountpoint. I don't understand how? > > | 2. Mount without new option "minstance"(for example) must keep old > behavior. Is it necessarily? > | Or every new mount will mount new instance? > > Sure, I don't have a problem with that. An option to mount a copy as opposed > to a separate instance is fine. Ok. One remark: mount one instance more than one time useless, because, which mount point must return TIOCPTMGET in this case? Maybe I don't understand fully NetBSD pty layer realization yet. > > christos > >