Meet Mach by James Scott, a summary of Mach's history and main concepts.
M. Accetta, R. Baron, W. Bolosky, D. Golub, R. Rashid, A. Tevanian, and M. Young, Mach: A New Kernel Foundation for UNIX Development, USENIX Conference Proceedings, July 1986. Paper [pdf].
R. Rashid, A. Tevanian, M. Young, D. Golub, and R. Baron, Machine-Independent Virtual Memory Management for Paged Uniprocessor and Multiprocessor Architectures, 2nd ACM Symposium on Architectural Support for Programming Languages and Operating Systems (ASPLOS), October 1987. Paper [pdf], presentation [ppt].
The Unofficial GNU Mach IPC beginner's guide, an easy introduction to Inter Process Comunication in the Mach microkernel by Manuel Pavón Valderrama.
Mach IPC without MIG, an exercise by Neal Walfield to understand Mach IPC at one of its lowest application levels.
- ipc-hello.c: Hello world à la mach ipc.
IRC, freenode, #hurd, 2013-09-15
<teythoon> braunr: btw, are there multiple kernel threads in gnumach? <teythoon> and is it safe to do a synchronous rpc call to a userspace server? <braunr> teythoon: there are yes, but few <braunr> teythoon: the main (perhaps only) kernel thread is the page daemon <braunr> and no, it's not safe to do synchronous calls to userspace <braunr> except to the default pager