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diff --git a/community/gsoc/2012/virt/discussion.mdwn b/community/gsoc/2012/virt/discussion.mdwn new file mode 100644 index 00000000..e0085322 --- /dev/null +++ b/community/gsoc/2012/virt/discussion.mdwn @@ -0,0 +1,389 @@ +[[!meta copyright="Copyright © 2012 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + + +# IRC, freenode, #hurd, 2012-07-19 + + <nowhere_man> well, I really actively started last week, so I'm ironing my + various use cases and above all I'm taking my barings in Hurd's code + <nowhere_man> I'm currently reading boot/ and pfinet/ + <braunr> sorry for asking but + <braunr> can you describe brielfy what you mean to achieve + <braunr> i know it sounds weird but the project description is a bit vague + for me + <nowhere_man> OK + <nowhere_man> the main goal is to be able to easily spawn a subhurd that's + connected in some way to its host + <braunr> ok + <nowhere_man> mainly connected by network, possibly sharing resources like + FS + <braunr> is it similar in spirit with something like linux containers ? + <nowhere_man> IIRC about them, yes + <braunr> ok + <braunr> that will do for me then + <tschwinge> Yes, so not complete virtualization, but instaed limitied to + several components. + <braunr> lxc with more runtime features to increase/decrease the level of + isolation + <nowhere_man> at first it would be static, at creation time only + <braunr> ok, i clearly understand the proposal now :) + <braunr> what kind of help could you need in the near future ? + <braunr> (except permanent access to youpi's brain?) + <tschwinge> Yes, that's my question, too -- what can we do to "get this + thing going". + <nowhere_man> by monday or tuesday I should be clear on what I understand + or not in the code + <nowhere_man> I'm still a bit up to my elbows in it + <nowhere_man> at that point I'll be happy to be able to pop a lot of + questions about it + <braunr> so you'll be ready for the next meeting + <nowhere_man> yeah + <tschwinge> Please do as soon as there are questions that you cannot + resolve in a reasonably short amount of time. + <tschwinge> So often a quick hint from someone else already helps to ge + un-stuck. + <nowhere_man> OK + <tschwinge> There is no problem with asking for help given this huge and + convoluted code-base, where often design decisions are not obvious, too. + <nowhere_man> I will + <tschwinge> Good. :-) + <antrik> nowhere_man: hm... what you said so far doesn't sound any + different than the work zhengda already did on boot years ago... + <antrik> (although none of it ever got upstream IIRC :-( ) + <nowhere_man> antrik: wasn't aware of it, is there some code published? + <tschwinge> There are bits and pieces, but certainly there is enough work + left to be done, to put it all together. + <antrik> yes, his git repository should be up somewhere. it's quite + convoluted though, as he worked on several things, and also wasn't very + experienced with revision control in the beginning + <tschwinge> nowhere_man: + http://www.gnu.org/software/hurd/community/gsoc/2008.html + <tschwinge> nowhere_man: http://www.gnu.org/software/hurd/user/zhengda.html + <tschwinge> Second section of the latter one. + <antrik> well, my understanding of the proposal (and more or less what I + was driving at in the project idea, which is rather vague admittedly) is + something lighter than a real subhurd... rather some kind of thin + subenvironment that doesn't actually boot a complete system instance with + various daemons etc. + <tschwinge> nowhere_man: It is certainly valid for you to use pre-existing + code/patches, by the way. + <antrik> BTW, regarding the "full subhurd" thing, the missing pieces are + mostly virtual device implementations + <antrik> (that and some tough bug(s) remaining in zhengda's modified + boot...) + <nowhere_man> cool, I'll take a look + <antrik> in any case, getting a picture of the work zhengda did is, is + definitely the first thing to do :-) + <tschwinge> nowhere_man: I'll also try to locate some bits and stuff from + his verious repositories (I just fond a Subverision one; will convert to + Git). + <antrik> tschwinge: I'm pretty sure zhengda's git repository was converted + from the SVN one... + <tschwinge> antrik: Thanks for reminding us about this -- I failed to + remember all that. + <antrik> (which was in turn converted from CVS...) + <tschwinge> antrik: OK, will have a lot. + <tschwinge> Yeah, found a CVS tree, too. ;-) + <antrik> BTW, zhengda's work more exactly was about subhurd without root + privileges. but that lays a lot of the groundwork for all kinds of more + flexible subhurd usage + <antrik> (but it's still quite a different thing that thing + subenvironments, so don't get confused...) + <antrik> err... thin subenvironments + + +# IRC, freenode, #hurd, 2012-07-27 + + <nowhere_man> bddebian: I'm actually not progressing much while reading the + source, I'm jumping all over the place to grasp the various types and + functions used where I start + <nowhere_man> would there be a few starting points that could help me? + <tschwinge> nowhere_man: So what exactly is your status; what are you + doing, what do you need help with? We surely can provide help, but need + to know where. + <nowhere_man> I'm starting from the source of boot/ and pfinet/ and as soon + as I encounter something that I don't understand, I find its definition + <nowhere_man> I'm kind of doing a depth-first search of what I need to + understand in the source code + <nowhere_man> I'm wondering if there are a few places in the source code + that I should start reading before anything else + <nowhere_man> well, I'll have to go in a few minutes + <nowhere_man> I'll continue my DFS ;-) + + +# IRC, freenode, #hurd, 2012-08-02 + + <nowhereman> well, I made a leap forward in understanding the code, when I + stopped my DFS + <nowhereman> in hindsight, I'd say my way of approaching the code was + probably one of the worst possible + <braunr> oh + <tschwinge> OK, so at least you learned something, which is good. + <tschwinge> So, what's the new approach? And what are you working on at + the moment + <tschwinge> ? + <nowhereman> I just remembered SICP, the idea of wishful thinking when you + code, and didn't bother with the fine details behind what I'm reading + <nowhereman> like, I don't really get what happens when a Mach port is + allocated, but I know approximately what a Mach port is + <tschwinge> So originally you worked on investigating all that, every line + of code? + <nowhereman> almost, yeah + <braunr> nowhereman: again, feel free to ask + <tschwinge> Yes indeed -- that's too complex for a single person to tackle + at one time. + <braunr> and quickly + <braunr> don't loose time + <tschwinge> Not even braunr and I have looked up all these things. + (Speaking for Richard here, but I'm quite sure he'll agree. Perhaps he + has in fact looked up all the Mach things, though.) + <tschwinge> nowhereman: ufc? + <nowhereman> BTW, last week I wanted to push my description of how the tool + could be used, the use cases + <nowhereman> ufs + <nowhereman> but flubber is not online + <tschwinge> nowhereman: Oh, why ufs specifically? + <braunr> don't waste time on ufs + <braunr> really + <tschwinge> nowhereman: Yes, flubber is down. But you can push directly to + the Savannah repository. + <tschwinge> nowhereman: Please immediatelly tell us if you're stuck on + something, like flubber not being available. + <tschwinge> We may not be able to help immediatelly, but we're the at least + aware of issues. + <braunr> and we may be able to help immediately :) + <tschwinge> As we're not sitting in a lab next to each other, we can't tell + otherwise what's going on. + <tschwinge> We may in fact even be able to tell you immediatelly to use + Savannah instead of flubber, indeed. + <tschwinge> nowhereman: So, back to ufs -- which you don't specifically + need to look at, I think -- ext2fs is what everyone uses. But even there + you shouldn't really need to know many details/internals. + <nowhereman> OK, I was looking into it has it appears in hurd.boot + <tschwinge> Ah, OK. Yeah, that's just an example/template, and should use + ext2fs nowadays. + <nowhereman> in fact, as far as FS are concerned, I suppose I will merely + need to know how to pass a port to the host's FS to some proxy FS in the + subhurd + <nowhereman> mmmh, Savannah only mentions a hurd.git + <tschwinge> Exactly that is the abstraction level you need, yes. + <nowhereman> I'm looking at http://savannah.gnu.org/git/?group=hurd + <tschwinge> Yeah, that's a known shortcoming -- look here instead: + http://git.savannah.gnu.org/cgit/hurd + <tschwinge> Here is some more up-to-date stuff on subhurds: + http://www.gnu.org/software/hurd/hurd/subhurd.html + <tschwinge> nowhereman: You know how to tell git to add a new remote to + your web pages checkout and such stuff? + <nowhereman> yeah, no problem with that + <braunr> have you prepared any question to ask us ? + <nowhereman> the only I have now is if you can tell me where to look in the + code about passing Mach ports + <braunr> you don't pass ports, you pass rights + <braunr> http://www.gnu.org/software/hurd/gnumach-doc/index.html is the + best location to have a look at + <braunr> + http://www.gnu.org/software/hurd/gnumach-doc/Exchanging-Port-Rights.html#Exchanging-Port-Rights + <braunr> i suppose the mig doc will help too, as you may be using a higher + level interface to exchange rights + <braunr> be careful about user references on port rights + <braunr> deallocate releases a reference, it doesn't immediately destroy a + resource + <braunr> portinfo -v can help monitoring a task's rights + <braunr> nowhereman: so what are you planning to do now ? + <braunr> during the next week + <nowhereman> documenting what I understand from the boot process and where + things can be changed to fit my various use cases + <braunr> do you expect that to take the whole week ? + <nowhereman> and doing some first modifications to servers for the simplest + cases + <braunr> ok + <braunr> well i hope you're able to really start working on it soon, and + won't face weird issues in the meantime + <braunr> i'm a bit disappointed that you don't have more questions + <braunr> my feeling is you either did understand everything (except passing + port rights), or you didn't attempt to seriously understand the code + <braunr> or you don't dare ask questions + <braunr> this is something that must change + <braunr> or these meetings won't be as useful as they could be + <tschwinge> Yes. But also please don't wait for the meetings, but ask + questions throughout the week, too. + + +# IRC, freenode, #hurd, 2012-08-09 + + <nowhere_man> hey, does anyone knows the network device interface well? + <nowhere_man> I don't get it by reading net_io.c/h in gnumach + <braunr> nowhere_man: ask your question + <braunr> nowhere_man: http://www.sceen.net/~rbraun/pcap-hurd.c <- this may + help + <nowhere_man> I don't see what the entry point is + <nowhere_man> I finally understood that I actually don't need to touch + pfinet for gsoc project + <nowhere_man> but I should do a replacement network device instead + <nowhere_man> is the net_io_init function called at start? + <braunr> what entry point ? + <braunr> and you should perhaps have a look at the eth-multiplexer by + zhengda + <braunr> yes net_io_init is called at startup + <braunr> nowhere_man: did you find your answers about networking ? + <nowhere_man> no, I'm still digging in mach's code + <braunr> nowhere_man: well keep asking :/ + <braunr> you left conversation without notice :/ + <braunr> nowhere_man: and why mach ? + <nowhere_man> I thought hardware devices are there + <tschwinge> nowhere_man: You wanted to push your documentation one/two + weeks ago. Why has that not yet happened? + <youpi> nowhere_man: they used to be there, they are now in netdde, but in + both case it's just a matter of the same RPC interface + <nowhere_man> tschwinge: I spent very few time this week on gsoc, and + completely forgot about the push on savannah + <braunr> nowhere_man: i told you to look at the work by zhengda concerning + eth-multiplexer, did you do that ? + <tschwinge> nowhere_man: You realize GSoC is meant to be a full-time job? + <tschwinge> Or, next to full-time? + <braunr> it's full-time normally + <braunr> the payment is justified by that + <youpi> nowhere_man: most RPC operations you need to know about network can + be seen at work in pfinet/ethernet.c, wherever "ether_port" appears + <youpi> i.e. device_open, set_filter, write, set/get_status + <braunr> again, http://www.sceen.net/~rbraun/pcap-hurd.c should guide you + pretty well + <braunr> since it's the very least necessary to use that interface + <tschwinge> nowhere_man: How, roughly but realistically, are your plans to + continue this task? + <tschwinge> nowhere_man: What has been blocking you this week so you + couldn't work on your task? + <nowhere_man> tschwinge: mostly a previous work that was supposed to end at + the beginning of the summer and only went online now, for which I'm + basically sysadmin + <braunr> 21:25 < tschwinge> nowhere_man: How, roughly but realistically, + are your plans to continue this task? + <braunr> this question is really more interesting actually + <nowhere_man> right now, I want to write a netword device that just sends + its frames by IPC + <braunr> why ? + <nowhere_man> as I never wrote any program using Mach's IPC, that seems the + easiest to get them right + <braunr> you won't have time + <braunr> 21:22 < braunr> nowhere_man: i told you to look at the work by + zhengda concerning eth-multiplexer, did you do that ? + <nowhere_man> braunr: not yet, no + <braunr> well that's your best chance to make some progress + <nowhere_man> braunr: is writing the virtal network device that hard? + <braunr> basically, it allows "bridgind" the pfinet instances of various + subhurds + <braunr> the virtual network device you want *is* eth-multiplexer + <tschwinge> nowhere_man: GSoC is nearly over. That's why I'm asking how + this task is going to continue. I'm sorry but I reckon you have not + spend anywhere near the amount of hours that are meant to be spent on it. + <braunr> and from what antrik told me, yes it's hard, and moreover, why + rewrite it if it already exists and you're late + <braunr> i agree + <nowhere_man> tschwinge: I know, I've started way too late because of my + second round of exams + <tschwinge> nowhere_man: OK, that's how you started. But how is it going + to continue... + <nowhere_man> tschwinge: in short, I write a prototype that just starts a + subhurd, and when that works correctly I add the network + <tschwinge> nowhere_man: I mean from an organizational point of view. + <nowhere_man> well, between now and the beginning of september, I'll work + full-time on this + <nowhere_man> up until september 8th + + +# IRC, freenode, #hurd, 2012-08-09 + + <antrik> nowhere_man: you do *not* have to do a replacement network + device. zhengda did that years ago. + <antrik> nowhere_man: also note that zhengda also implemented the support + for *using* the virtual network device (in fact any replacement devices + -- except that no others actually exist yet) in boot + <youpi> which is already in, actually, isn't it? + <antrik> youpi: hm, yes... it was the patch that zhengda posted on the list + once, but later updated, and at some later point you merged the outdated + variant from the list... + <youpi> outdated? + <youpi> ah, but he never posted the updated one, and it got lost in git + repos, right? + <youpi> (what was updated actually?) + <antrik> he changed the option name and description later for more + clarity. don't remember whether there were other changes + <antrik> -f, --device=device_name=device_file + <antrik> Specify a device file used by subhurd + and its + <antrik> virtual name. + <antrik> that's the one from the Debian package + <antrik> -m, --device-map=DEBICENAME=DEVICEFILE + <antrik> Map the device in subhurd to the + device in the + <antrik> main Hurd. + <antrik> that's the one I have locally built from his tree + <youpi> so you actually have access to his tree? + <antrik> uhm... I used to... it was on flubber + + +# IRC, freenode, #hurd, 2012-08-18 + + <nowhere_man> so, this week I discovered how fun it is to work on a + non-mainstream OS + <nowhere_man> I hoped to start coding the tool itself, put together the + skeleton, but every Lisp implementation I tried had problems + <braunr> ah you want to write it in lisp ? + <nowhere_man> ECL, that I had ported a few years ago, actually FTBFS since + <nowhere_man> I hoped to be able, it would be easier for me + <nowhere_man> and when I tried Scheme, I started with Guile (it's GNU's own + Scheme implementation, after all) + <nowhere_man> and when I execute the FFI functions, to access functions in + libmachdec + <nowhere_man> I get SIGILL + <braunr> i can't advise you about anything lisp related + <braunr> the most reliable thing you'll find on the hurd is C + <nowhere_man> I tried to debug that, but running Guile in GDB gets me a + SIGSEV + <nowhere_man> I'll try to make ECL to build again + <braunr> this seems like a waste of time to me + <braunr> avoid spending time on anything that isn't directly related to + your goal if you still hope to finish it + <nowhere_man> I'm ten times more comfortable coding in Lisp + <braunr> it doesn't matter, you're late + <nowhere_man> yeah, I know, so taking the time to correct that problem + won't change the fact that I won't finish in time + <nowhere_man> so I'll finish anyway, and in Lisp + <braunr> and if you lack something else, like some mach/hurd specific lisp + bindings, you'll have to spend more time on that + <braunr> ok + <nowhere_man> do you know if someone had a SIGILL situation on Hurd in the + past? + <nowhere_man> I'm wondering if that's a known kind of issue + <braunr> there are lots of issues + <braunr> especially when it comes to other languages and runtime + environments + <nowhere_man> but is it like MAX_PATH_LEN, something that is known to + happen when porting something on Hurd? + <braunr> i'm not sure how comparable it is + <braunr> i'd say it's often before of the conformance issues of the hurd + <braunr> because* + <nowhere_man> like missing bits of POSIX ? + <braunr> or simple wrong for some corner cases + <braunr> simply* + <bubu^> nowhere_man, I was able to run guile on my hurd image through qemu + <bubu^> but I didn't make any complexe programms to check if everything + works fine + <nowhere_man> yeah, it runs fine + <nowhere_man> FFI functions get you a SIGILL + <nowhere_man> + http://www.gnu.org/software/guile/manual/html_node/Dynamic-FFI.html + <nowhere_man> the define-module form at the beginning triggers the signal + <antrik> nowhere_man: what do you want to implement in Lisp? + <antrik> BTW, the guy working on Lisp bindings a couple of years ago used + Clisp + <antrik> it was working back then + <nowhere_man> antrik: the program that sets up a subhurd + <nowhere_man> I always forget about clisp, I'll try it right away |