Re: Issues with capability bits and meta-data in kdbus

From: Austin S Hemmelgarn
Date: Wed Apr 22 2015 - 10:06:12 EST


On 2015-04-22 09:07, Greg Kroah-Hartman wrote:
On Wed, Apr 22, 2015 at 07:40:25AM -0400, Austin S Hemmelgarn wrote:
On 2015-04-21 22:32, Linus Torvalds wrote:
On Tue, Apr 21, 2015 at 6:54 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:

If kdbus were a general purpose IPC tool

.. but it's not ..


Except, IIRC, that was one of the stated design goals in the original patch
set. I'm pretty sure that i remember a rather verbose exposition that
pretty much could be summarized as "Linux has no general purpose IPC in the
kernel, this fixes that"

Did I say that somewhere? Here's what the patchset has always started
with every time I have posted it for review, starting back last year in
October:

kdbus is a kernel-level IPC implementation that aims for
resemblance to the the protocol layer with the existing
userspace D-Bus daemon while enabling some features that
couldn't be implemented before in userspace.

2+ years ago, I had the dream that maybe we could make kdbus into the
"general purpose IPC layer for the kernel", but in working through all
of the issues, and the requirements of the userspace users and
protocols, it just really didn't work out that way, sorry.

I think it may have been someone else elaborating on this ideal that I was remembering. Personally, I could care less whether it is considered 'general purpose', as far as I'm concerned, POSIX semaphores, shm, and UDS fit all the IPC I ever need. On that note, I have considered trying to implement SOCK_SEQPACKET support for AF_LOCAL, although I've gotten by just fine using SCTP over the loop-back interface.

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