On Tue, Jan 20, 2015 at 9:31 AM, David Herrmann <dh.herrmann@xxxxxxxxx> wrote: > Hi Michael > > On Tue, Jan 20, 2015 at 2:53 PM, Michael Kerrisk (man-pages) > <mtk.manpages@xxxxxxxxx> wrote: >> On 01/16/2015 08:16 PM, Greg Kroah-Hartman wrote: >>> From: Daniel Mack <daniel@xxxxxxxxxx> >>> >>> kdbus is a system for low-latency, low-overhead, easy to use >>> interprocess communication (IPC). >>> >>> The interface to all functions in this driver is implemented via ioctls >>> on files exposed through a filesystem called 'kdbusfs'. The default >>> mount point of kdbusfs is /sys/fs/kdbus. This patch adds detailed >>> documentation about the kernel level API design. >> >> I have some details feedback on the contents of this file, and some >> bigger questions. I'll split them out into separate mails. >> >> So here, the bigger, general questions to start with. I've arrived late >> to this, so sorry if they've already been discussed, but the answers to >> some of the questions should actually be in this file, I would have >> expected. >> >> This is an enormous and complex API. Why is the API ioctl() based, >> rather than system-call-based? Have we learned nothing from the hydra >> that the futex() multiplexing syscall became? (And kdbus is an order >> of magnitude more complex, by the look of things.) At the very least, >> a *good* justification of why the API is ioctl()-based should be part >> of this documentation file. >> >> An observation: The documentation below is substantial, but this API is >> enormous, so the documentation still feels rather thin. What would >> really help would be some example code in the doc. >> >> And on the subject of code examples... Are there any (prototype) >> working user-space applications that exercise the current kdbus >> implementation? That is, can I install these kdbus patches, and >> then find a simple example application somewhere that does >> something to exercise kdbus? > > If you run a 3.18 kernel, you can install kdbus.ko from our repository > and boot a full Fedora system running Gnome3 with kdbus, given that > you compiled systemd with --enable-kdbus (which is still > experimental). No legacy dbus1 daemon is running. Instead, we have a > bus-proxy that converts classic dbus1 to kdbus, so all > bus-communication runs on kdbus. FWIW, we've been building a "playground" repository for the kernel that contains this already for Fedora. If you have a stock Fedora 21 or rawhide install, you can use: https://copr.fedoraproject.org/coprs/jwboyer/kernel-playground/ which has the kernel+kdbus and systemd built with --enable-kdbus already. Easy enough to throw in a VM for testing. josh -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
