[RFC][PATCH 7/8]: Auto-create ptmx node when mounting devpts
H. Peter Anvin
hpa at zytor.com
Thu Aug 21 09:09:19 PDT 2008
Alan Cox wrote:
>> This patch has the kernel internally create the [ptmx, c, 5:2] device
>> when mounting devpts filesystem. The permissions for the device node
>> can be specified by the '-o ptmx_mode=0666' option. The default mode
>> is 0666.
>> Hopefully, presence of the 'ptmx' node in /dev/pts does not surprise
>> user space.
> If you are going to make major changes requiring user space changes to
> use them then you can change the user space rather than playing "gee
> where did that come from" with the existing system.
This particular one I think is the right thing, despite everything. In
particular, it makes a *hell* of a lot more sense to have this
auto-created, than supporting mknod(2) inside the devpts filesystem.
It's not a matter of "changing the user space"; it's a matter of what
makes most sense inside the kernel.
His new implementation doesn't require user space changes unless you
want to take advantages of the multi-instance features. It thus allows
for a soft transition. However, soft or hard transition is irrelevant
-- creating ptmx inside devpts is necessary, and it doesn't make sense
to require userspace to mknod it, since the kernel code ends up being
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