RFD: Rework/extending functionality of mdev

[James Bowlin]

On Sun, Mar 15, 2015 at 08:06 PM, Laurent Bercot said:
> > kernel guaranties not only atomicity for write operations, but also
> > for read operations (not in POSIX, AFAIK). 
                         ^^^^^^^^^^^^^^^^^^^^ 
>   Second sentence of
>   http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html :
                ^^^^^^^^^^^^^
For goodness sake.  This appears to be an argument merely for the
sake of having an argument.

> If, say, Linux has documentation somewhere explaining what it
> does with multiple readers on a pipe, [...]

A simple Internet search brings up the Linux fifo man page:
http://man7.org/linux/man-pages/man7/fifo.7.html

    A FIFO special file (a named pipe) is similar to a pipe,
    except that it is accessed as part of the filesystem.  It can
    be opened by multiple processes for reading or writing.

> [....] and committing to NOT changing that behaviour EVER,

IMO this is a ridiculous demand that can't ever be met by
any software.

For my users the current busybox mdev hotplugging is not 100%
reliable (more like 99+% reliable) which is a big pain.  I'd love
to see other busybox hotplug solutions that are selectable at
runtime.

You both have a lot of value to contribute.  If both/all
solutions can be (via compile-time options) available at runtime
and one is clearly superior to the others then that will be
quickly figured out.

It is very kind to try to help someone else from wasting time
on a technically inferior solution but at some point it is
better for everyone to just let them go ahead and use their
time as they see fit.


Peace, James