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@@ -40,3 +40,198 @@ Richard's X-15 Mach re-implementation:
the whole talk; but they mentioned similar possibilities to what I'm
envisioning here :-)
+## IRC, freenode, #hurd, 2012-03-28
+ <mel__> is there currently any work going on with respect to
+ Mach-alternatives?
+ <antrik> mel__: no
+ <antrik> we have other priorities to take care of :-)
+ <braunr> antrik: i still intend to try giving linux a "mach personality" :)
+ <braunr> antrik: but i don't have much time for development currently :(
+ <mel__> antrik: which means that the hope is that Mach can be turned into
+ something really well working (i.e. secure/scalable/etc.)?
+ <antrik> mel__: yes, that's the venue we are pursuing
+ <antrik> (and IMHO the right one... though the Linux layer mentioned by
+ braunr is also one of my favourite projects, that we should pursue *in
+ parallel* to the existing Mach-based implementation)
+ <mel__> what is this Linux Layer exactly?
+ <mel__> a Linux instance running on top of Mach in parallel to Hurd
+ serverS?
+ <braunr> mel__: not exactly
+ <braunr> mel__: it would involve adding a mach layer on top of linux
+ actually
+ <braunr> mel__: so that linux can be used as a mach kernel
+ <mel__> Ah!
+ <mel__> Running Hurd on top of Linux
+ <mel__> :-D
+ <mel__> Funny
+ <braunr> ironic, yes
+ <braunr> but very pragmatic
+ <mel__> and THEN
+ <antrik> yeah. I most like the name: Hurd Emulation Layer on
+ Linux... i.e. HELL :-)
+ <mel__> we use a device driver framework something so that we can use Linux
+ device drivers in Hurd!
+ <mel__> on top of Linux....
+ <braunr> yes
+ <braunr> i guess a transition phase would include using in kernel drivers
+ directly for a while
+ <mel__> and somebody is working on that?
+ <antrik> mel__: well, for using Linux drivers we are persuing DDE, which
+ allows us doing that with Mach as well
+ <braunr> then grabbing them out of the kernel and into dde
+ <braunr> not yet
+ <antrik> (in fact we have been using Linux drivers since forever... they
+ just haven't been updated for ages)
+ <mel__> I would _guess_ that it is not that hard.
+ <braunr> it's not
+ <mel__> Basically one would need to implement the message passing interface
+ thing in linux I guess.
+ <braunr> and many exported kernel objects like tasks, threads, etc..
+ <braunr> and implement all the RPCs normally implemented by the kernel
+ <braunr> but it's doable
+ <antrik> mel__: the IPC aspect is one part, but probably the less tricky
+ one. the external pager interface is really the crucial element
+ <mel__> uh
+ <mel__> yeah
+ <mel__> hooking into linux virtual memory stuff
+ <mel__> sounds delicate
+ <braunr> it's true that some interactions between the linux VM and file
+ systems (the linux equivalent of our pagers) is synchronous
+ <braunr> but i don't think it would be that hard considering the amount of
+ facilities available in linux
+ <braunr> it's just work, takes time, needs debugging, reviewing, testing,
+ etc..
+ <lcc> hurd on top of linux. how would that work?
+ <braunr> 15:30 < braunr> antrik: i still intend to try giving linux a "mach
+ personality" :)
+ <braunr> lcc: 7 system calls and a few hundreds of RPCs on top, the
+ internal magic of course, and voila ..
+ <antrik> of course porting Mach still requires work
+ <mel__> that would then be GNU/Hurd/Linux
+ <mel__> :-)
+ <antrik> hehe
+ <braunr> eh
+ <antrik> braunr: BTW, are you more thinking of a userspace solution on top
+ of standard Linux mechanisms, or additions to Linux itself?...
+ <antrik> (we probably talked about it already, but I don't remember all the
+ details...)
+ <braunr> antrik: adding to linux
+ <antrik> do you think a pure userspace solution would be realistic at all?
+ (at the expense of some performance of course)
+ <mel__> it's probably comparable to the qemu vs. qemu/kvm thing
+ <antrik> yeah, I guess that pretty much sums it up...
+ <braunr> antrik: i don't know :/
+ <antrik> OK
+ <lcc> how challenging is it to port mach?
+ <antrik> lcc: it requires good low-level knowledge of the platform in
+ question. having that, I guess it shouldn't be too hard to add the
+ necessary code in Mach...
+ <antrik> TBH I'm not sure how much knowledge of Mach internals is required
+ <braunr> the pmap module is the main thing to port
+ <antrik> braunr: well, sartakov seemed to have most trouble with the
+ scheduler when he attempted the ARM port...
+ <braunr> that's strange
+ <antrik> at least there was quite a long thread where he asked about how
+ task switching works in Mach
+ <braunr> ok
+ <braunr> that would be interesting
+ <braunr> i thought intereacting with the hardclock was enough
+## IRC, freenode, #hurd, 2012-04-05
+ <braunr> antrik: don't you think HELL is worth a try for the GSoC btw ?
+ <antrik> braunr: definitely. I haven't managed to rework the project ideas
+ list at all this year... but it's something I wanted there for a long
+ time
+ <youngrw> just out of curiousity, what is HELL ?
+ <antrik> Hurd Emulation Layer on Linux
+ <braunr> youngrw: it can be described in several ways
+ <braunr> youngrw: basically, it's a mach interface on top of linux
+ <youngrw> implementing I suppose both the IPC mechanism and memory
+ management interface?
+ <mel__> youngrw: basically that. more generally: implement everything in
+ order to let Hurd run on that layer.
+ <antrik> well, it's slightly more complicated in my view... it's basically
+ anything that allows running a Hurdish environment on top of
+ GNU/Linux. it might be simply an implementation/emulation of Mach
+ mechanisms; but it also *might* work on a slightly higher level...
+ <youngrw> antrik: how might HELL operate at the slighty higher level like
+ you describe?
+ <antrik> let's call it low-level HELL and high-level HELL ;-)
+ <antrik> (a more descriptive name would be hurdenv... but HELL is so much
+ more catchy :-) )
+ <antrik> so, high-level HELL... basically, the idea would be not to emulate
+ the kernel facilities and run all the real Hurd servers; but instead to
+ use special servers implementing the Hurd interfaces, but on top of
+ standard Linux facilities
+ <antrik> hurdish programs could run in such an environment, as long as they
+ aren't too low-level
+ <antrik> I wonder whether generic RPC interfaces could be implemented with
+ some side channel tunneled though the ordinary Linux FS interfaces...
+ <antrik> so translators would be loaded as FUSE modules for example, but
+ could still present generic interfaces
+ <youngrw> That's actually pretty different from what I was expecting
+ <antrik> what were you expecting?
+ <youngrw> maybe something where the entire kernel interface is emulated by
+ a running user process, like a kind of virtual machine
+ <youngrw> I hope that makes sense--I may be using my words incorrectly.
+ <antrik> youngrw: that would be in the low-level HELL category
+ <youngrw> antrik: right; I had the misconception that the level was defined
+ by how it made use of the underlying linux system
+ <youngrw> and that different HELL designs would always implement the mach
+ interface
+## IRC, freenode, #hurd, 2012-04-06
+ <braunr> antrik: i think we have diverging ideas about how to use linux for
+ the hurd
+ <braunr> antrik: what you seem to want are really emulation componants,
+ like e.g. ext2fs and pfinet actually using the linux implementation
+ <braunr> (correct me if i'm mistaken)
+ <braunr> whereas my project is to make linux behave as a mach clone
+ <antrik> braunr: as I said, I consider both variants -- either a high-level
+ HELL or a low-level HELL
+ <braunr> ok
+ <antrik> (or perhaps a mix of both)
+ <braunr> a mix would be best imho
+ <antrik> yeah, probably
+ <braunr> so we have the real hurd, the real mach interface, and a set of
+ native translators (e.g. ext2fs) along some emulating their functionality
+ using linux code (e.g. a hypothetical ext4fs)
+ <antrik> I don't think we would have emulation servers for individual Linux
+ filesystems. rather, a generic server interfacing with the Linux VFS
+ tree...
+ <braunr> ok
+ <antrik> braunr: BTW, I think I mentioned a couple of years ago that the
+ most realistic route towards a modern Mach in my opinion would be taking
+ a modern BSD (or Linux), and redo what the original Mach developers did
+ -- i.e. add the Mach-specific features, and drop the unnecessary UNIX
+ stuff
+ <braunr> antrik: :)
+ <braunr> we had discussions about it some time ago yes
+ <antrik> later I realised that it's better *not* to drop the UNIX
+ interfaces, but rather to keep them in parallel :-)
+ <braunr> antrik: for what purpose ?
+ <braunr> (i can imagine a few, but i'd like to know your idea)
+ <antrik> for the purpose of HELL :-)
+ <braunr> well hell would be the implementation, but what do you keep these
+ unix interfaces for ?
+ <antrik> i.e. people being able to play around with a Hurd environment
+ while staying with their existing system
+ <braunr> yes, i see
+ <braunr> i was considering doing that for development, yes
+ <braunr> uml first, and then i realized i wouldn't need it :)
+ <braunr> then i remembed netbsd and its syscall emulation layer
+ <antrik> also we might leverage some "foreign" userspace infrastructure
+ that way, such as udev
+ <antrik> (in the case of Linux that is... not sure whether NetBSD has
+ something similar at all ;-) )
+ <braunr> i'll have to check, it's been a long time since i've really used
+ it
+ <braunr> they must use a pure devfs instance now