Off-topic: D-Bus in the kernel

Rémi Denis-Courmont remi at
Wed Sep 15 21:37:33 PDT 2010


On Thursday 16 September 2010, Soh Kam Yung wrote:
> Just spotted this interesting post about putting d-bus in the kernel [
> ]

Unfortunately, the D-Bus bus is too feature-bloated to be implemented in 
kernel. For one thing, routing messages will be no fun, the kernel would have 
to parse and keep track of the AddMatch requests. Arguably, a kernel-space D-
Bus should implement signal subscription out-of-band (compare to the IP 
multicast ioctl()s). But then it's not really the D-Bus protocol anymore.

Feature negotiation will also make a kernel implementation more difficult. It 
means more messages to parse and more state to keep in kernel.

But I expect the worst part of a kernel D-Bus to be the security enforcement. 
Parsing files in kernel space is a complete non-starter, and that includes 
service files. So it might be possible to move the session bus to kernel space, 
but I am not very optimistic about the system bus. Hmm, anyone for dbustables 
and NetFilter-DBus?

Also, this article contains some highly suspicious inaccuracies. skb_clone() 
does not copy message buffers, only buffer heads.

Rémi Denis-Courmont

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