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diff --git a/open_issues/dde.mdwn b/open_issues/dde.mdwn index e2cff94f..adb070cd 100644 --- a/open_issues/dde.mdwn +++ b/open_issues/dde.mdwn @@ -1,4 +1,5 @@ -[[!meta copyright="Copyright © 2010, 2011 Free Software Foundation, Inc."]] +[[!meta copyright="Copyright © 2010, 2011, 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 @@ -13,3 +14,350 @@ License|/fdl]]."]]"""]] [[General Information|/dde]]. Still waiting for interface finalization and proper integration. + +[[!toc]] + + +# Upstream Status + + +## IRC, freenode, #hurd, 2012-02-08 + +At the microkernel davroom at [[community/meetings/FOSDEM_2012]]: + + <antrik> there was quite some talk about DDE. I learnt that there are newer + versions in Genode and in Minix (as opposed to the DROPS one we are + using) + <antrik> but apparently none of the guys involved is interested in creating + a proper upstream project with central repository and communication + channels :-( + <antrik> the original DDE creator was also there, but said he isn't working + on it anymore + <tschwinge> OK, and the other two projects basically have their own forks. + <tschwinge> Or are they actively cooperating? + <tschwinge> (If you know about it.) + <antrik> well, Genode is also part of the Dresden L4 group; but apart from + that, I'd rather call it a fork... + <antrik> hm... actually, I'm not sure anymore whether the guy I talked to + was from Genode or Nova... + <antrik> (both from the Dresdem L4 group) + + +## IRC, freenode, #hurd, 2012-02-19 + + <youpi> antrik: do we know exactly which DDE version Zheng Da took as a + base ? + <youpi> (so as to be able to merge new changes easily) + <antrik> youpi: not sure... but from what I gathered at FOSDEM, the version + he based on (from DROPS) is not really actively developed right now; if + we want to go for newer versions, we probably have to look at other + projects (like Genode or Nova or Minix) + <youpi> there's no central project for dde ? + <youpi> that sucks + <antrik> no... and nobody seemed interested in having one :-( + <youpi> pff + <antrik> which makes me seriously question the original decision to build + on DDE... + <braunr> .. + <antrik> if we have to basically maintain it ourselfs anyways, we could + just as well have gone with custom glue + <youpi> well, the advantage of DDE is that it already exists now + <antrik> on the positive side, one of the projcets (not sure which) + apparently have both USB and SATA working with some variant of DDE + + +# IRC, OFTC, #debian-hurd, 2012-02-15 + + <pinotree> i have no idea how the dde system works + <youpi> gnumach patch to provide access to physical memory and interrupts + <youpi> then userland accesses i/o ports by hand to drive things + <youpi> but that assumes that no kernel driver is interfering + <youpi> so one has to disable kernel drivers + <pinotree> how are dde drivers used? can they be loaded on their own + automatically, or you have to settrans yourself to setup a device? + <youpi> there's no autoloader for now + <youpi> we'd need a bus arbitrer that'd do autoprobing + <pinotree> i see + <pinotree> (you see i'm not really that low level, so pardon the flood of + posssibly-noobish questions ;) ) + <youpi> I haven't set it up yet, but IIRC you need to specify which driver + to be used + <youpi> well, I mostly have the same questions actually :) + <youpi> I just have some guesswork here :) + <pinotree> i wonder whether the following could be feasible: + <youpi> I'm wondering how we'll manage to make it work in d-i + <pinotree> a) you create a package which would b-d on linux-source, build a + selection of (network only for now) drivers and install them in + /hurd/dde/ + <youpi> probably through a choice at the boot menu + <youpi> I wouldn't dare depending on linux-source + <youpi> dde is usually not up-to-date + <pinotree> b) add a small utility over the actual fsys_settrans() which + would pick the driver from /hurd/dde/ + <pinotree> ... so you could do `set-dde-driver b43 <device>` (or something + like that) + <youpi> we can provide something like b) yes + <youpi> although documenting the settrans should be fine enough ;) + <pinotree> the a) would help/ease with the fact that you need to compile on + your own the drivers + <pinotree> otherwise we would need to create a new linux-dde-sources-X.Y.Z + only with the sources of the drivers we want from linux X.Y.Z + <pinotree> (or hurd-dde-linux-X.Y.Z) + <CIA-4> samuel.thibault * raccdec3 gnumach/debian/ (changelog + patches/70_dde.patch patches/series): + <CIA-4> Add DDE experimental support + <CIA-4> * debian/patches/70_dde.patch: Add experimental support for irq + passing and + <CIA-4> physical memory allocation for DDE. Also adds nonetdev boot + parameter to + <CIA-4> disable network device drivers. + <youpi> ok, boots fine with the additional nonetdev option + <youpi> now I need to try that dde hurd branch :) + <CIA-4> samuel.thibault * rf8b9426 gnumach/debian/patches/70_dde.patch: Add + experimental.defs to gnuamch-dev + + +# IRC, freenode, #hurd, 2012-02-19 + + * youpi got dde almost working + <youpi> it's able to send packets, but apparently not receive them + <youpi> (e1000) + <youpi> ok, rtl8139 works + <youpi> antrik: the wiki instructions are correct + <youpi> with e1000 I haven't investigated + <antrik> (Archhurd guys also reported problems with e1000 IIRC... the one I + built a while back works fine though on my T40p with real e1000 NIC) + <antrik> maybe I should try with current versions... something might got + broken by later changes :-( + <youpi> at least testing could tell the changeset which breaks it + <youpi> Mmm, it's very odd + <youpi> with the debian package, pfinet's call to device_set_filter returns + D_INVALID_OPERATION + <youpi> and indeed devnode.c returns that + <youpi> ah but it's libmachdev which is supposed to answer here + <antrik> youpi: so, regarding the failing device_set_filter... I guess you + are using some wrong combination of gnumach and pfinet + <youpi> no it's actually that my pfinet was not using bpf + <youpi> I've now fixed it + <antrik> the DDE drivers rely on zhengda's modified pfinet, which uses + devnode, but also switched to using proper BPF filters. so you also need + his BPF additions/fixes in gnumach + <antrik> OK + <youpi> that's the latter + <youpi> I had already fixed the devnode part + <youpi> but hadn't seen that the filter was different + <antrik> err... did I say gnumach? that of course doesn't come into play + here + <antrik> so yes, you just need a pfinet using BPF + <youpi> libmachdev does ;) + <antrik> I'm just using pfinet from zhengda's DDE branch... I think devnode + and BPF are the only modifications + <youpi> there's also a libpcap modification in the incubator + <youpi> probably for tcpdump etc. + <antrik> libpcap is used by the modified pfinet to compile the filter rule + <youpi> why does pfinet need to compile the rule ? + <youpi> it's libbpf which is used in the dde driver + <antrik> it doesn't strictly need to... but I guess zhengda considered it + more elegant to put the source rule in pfinet on compile it live, rather + than the compiled blob + <antrik> I probably discussed this with him myself a few years back... but + my memory on this is rather hazy ;-) + <antrik> err... and compile it live + <youpi> ah, right, it's only used when asking pfinet to change its filter + <youpi> but it does not need it for the default filter + <youpi> which is hardcoded + <antrik> I see + <antrik> when would pfinet change its filter? + * youpi now completely converting his hurd box to debian packages with dde + support + <youpi> on SIOCSIFADDR apparently + <youpi> to set "arp or (ip host %s)", + <antrik> well, that sounds like the default filter... + <youpi> the default filter does not choose an IP + <antrik> oh, right... pfinet has to readjust the filter when setting the IP + <youpi> arg we lack support for kernel options for gnumach in update-grub + <antrik> again, I have a vague recollection of discussing this + * youpi crosses fingers + <youpi> yay, works + <antrik> so we *do* need libpcap in pfinet to set proper rules... though I + guess it can also work with a static catchall rule (like it did before + zhengda's changes), only less efficient + <youpi> well in the past we were already catching everything anyway, so at + least it's not a regression :) + <antrik> right + + +# IRC, freenode, #hurd, 2012-02-20 + + <youpi> I was a bit wary of including the ton of dde headers in hurd-dev + <youpi> maybe adding another package for that + <youpi> but that would have delayed introducing the dde binaries + <youpi> probably we can do that for next upload + <pinotree> i can try to work on it, if is feasible (ie if the dde drivers + can currently be built from outside the hurd source tree) + <youpi> it should be, it's a matter of pointing its makefile to a place + where the make scripts and include headers are + <youpi> (and the libraries) + <pinotree> ok + <antrik> youpi: you mean DDEKit headers? + <antrik> pinotree: actually it doesn't matter where the dde-ified Linux + drivers are built -- libdde_linux26 and the actual drivers use a + completetly different build system anyways + <antrik> in fact we concluded at some point that they should live in a + separate repository -- but that change never happened + <antrik> only the base stuff (ddekit, libmachdev etc.) belong in the Hurd + source tree + <youpi> antrik: yes + <youpi> antrik: err, not really completely different + <youpi> the actual drivers' Makefile include the libdde_linux26 mk files + <youpi> the build itself is separate, though + <antrik> youpi: yes, I mean both libdde_linux26 and the drivers use a build + system that is completely distinct from the Hurd one + <youpi> ah, yes + <youpi> libdde_linux26 should however be shipped in the system + <antrik> ideally libdde_linux26 and all the drivers should be built in one + go I'd say... + <youpi> it should be easily feasible to also have a separate driver too + <youpi> e.g. to quickly try a 2.6 driver + <antrik> youpi: I'm not sure about that. it's not even dynamically linked + IIRC?... + <youpi> with scripts to build it + <youpi> it's not + <youpi> but that doesn't mean it can't be separate + <youpi> .a files are usually shipped in -dev packages + <antrik> youpi: ideally we should try to come with a build system that + reuses the original Linux makefile snippets to build all the drivers + automatically without any manual per-driver work + <youpi> there's usually no modification of the drivers themselves? + <youpi> but yeah + <youpi> "ideally", when somebody takes the time to do it + <antrik> unfortunately, it's necessary to include one particular + Hurd/DDE-specific header file in each driver :-( + <youpi> can't it be done through gcc's -include option? + <antrik> zhengda didn't find a way to avoid this... though I still hope + that it must be possible somehow + <antrik> I think the problem is that it has to be included *after* the + other Linux headers. don't remember the details though + <youpi> uh + <youpi> well, a good script can add a line after the last occurrence of + #include + <antrik> yeah... rather hacky, but might work + <youpi> even with a bit of grep, tail, cut, and sed it should work :) + <antrik> note that this is Hurd-specific; the L4 guys didn't need that + <youpi> what is it? + <antrik> don't remember off-hand + + +# IRC, freenode, #hurd, 2012-02-22 + + <youpi> antrik: AIUI, it should be possible to include all network drivers + in just one binary? + <youpi> that'd permit to use it in d-i + <youpi> and completely replace the mach drivers + <youpi> we just need to make sure to include at least what the mach drivers + cover + <youpi> (all DDE network drivers, I mean) + <youpi> of course that doesn't hinder from people to carefully separate + drivers in several binaries if they wish + <youpi> antrik: it does link at least, I'll give a try later + <youpi> yes it works! + <youpi> that looks like a plan + <youpi> throw all network drivers in a /hurd/dde_net + <youpi> settrans it on /dev/dde_net, and settrans devnode on /dev/eth[0-9] + <youpi> I'm also uploading a version of hurd which includes headers & + libraries, so you just need a make in dde_{e100,e1000,etc,net} + <youpi> (uploading it with the dde driver itself :) ) + <youpi> btw, a nice thing is that we don't really care that all drivers are + stuffed into a single binary, since it's a normal process only the useful + pages are mapped and actually take memory :) + <Tekk_> is that really a nice thing though? compared to other systems I + mean + <Tekk_> I know on linux it only loads the modules I need, for example. It's + definitely a step up for hurd though :D + <youpi> that's actually precisely what I mean + <youpi> you don't need to load only the modules you need + <youpi> you just load them all + <youpi> and paging eliminates automatically what's not useful + <youpi> even parts of the driver that your device will not need + <Tekk_> ooh + <Tekk_> awesome + <youpi> (actually, it's not even loaded, but the pci tables of the drivers + are loaded, then paged out) + + +# IRC, freenode, #hurd, 2012-02-24 + + <youpi> antrik_: about the #include <ddekit/timer.h>, I see the issue, it's + about jiffies + <youpi> it wouldn't be a very good thing to have a jiffies variable which + we'd have to update 100times per second + <youpi> so ZhengDa preferred to make jiffies a macro which calls a function + which reads the mapped time + <youpi> however, that break any use of the work "jiffies", e.g. structure + members & such + <youpi> actually it's not only after headers that the #include has to be + done, but after any code what uses the word "jiffies" for something else + than the variable + <youpi> pb is: it has to be done *before* any code that uses the word + "jiffies" for the variable, e.g. inline functions in headers + <youpi> in l4dde, there's already the jiffies variable so it's not a + problem + + +# IRC, OFTC, #debian-hurd, 2012-02-27 + + <tschwinge> I plan to do some light performance testing w.r.t. DDE + Ethernet. That is DDE vs. Mach, etc. + <youpi> that'd be good, indeed + <youpi> I'm getting 4MiB/s with dde + <youpi> I don't remember with mach + <tschwinge> Yes. It just shouldn't regress too much. + <tschwinge> Aha, OK. + + +## IRC, freenode, #hurd, 2012-02-27 + + <youpi> tschwinge: nttcp tells me ~80Mbps for mach-rtl8139, ~72Mbps for + dde-rtl8139, ~72Mbps for dde-e1000 + <youpi> civodul: ↑ btw + <ArneBab> youpi: so the dde network device is not much slower than the + kernel-one? + <civodul> youpi: yes, looks good + <ArneBab> rather almost the same speed + <youpi> apparently + <ArneBab> that’s quite a deal. + <ArneBab> what speed should it have as maximum? + <ArneBab> (means: does the mach version get out all that’s possible?) + <ArneBab> differently put: What speed would GNU/Linux get? + <youpi> I'm checking that right now + <ArneBab> cool! + <ArneBab> we need those numbers for the moth after the next + <youpi> Mmm, I'm not sure you really want the linux number :) + <youpi> 1.6Gbps :) + <ArneBab> oh… + <youpi> let me check with udp rather than tcp + <ArneBab> so the Hurd is a “tiny bit” worse at using the network… + <youpi> it might simply be an issue with tcp tuning in pfinet + <ArneBab> hm, yes + <ArneBab> tcp is not that cheap + <ArneBab> and has some pretty advanced stuff for getting to high speeds + <youpi> well, I'm not thinking about being cheap + <youpi> but using more recent tuning + <youpi> that does not believe only 1Mbps network cards exist :) + <ArneBab> like adaptive windows and such? + <ArneBab> :) + <youpi> yes + * ArneBab remembers that TCP was invented when the connections went over + phone lines - by audio :) + <youpi> yep + <ArneBab> what’s the system load while doing the test? + <youpi> yes, udp seems not so bad + <ArneBab> ah, cool! + <youpi> it's very variable (300-3000Mbps), but like on linux + <ArneBab> that pushing it into user space has so low cost is pretty nice. + * ArneBab thinks that that’s a point where Hurd pays off + <youpi> that's actually what AST said to fosdem + <youpi> he doesn't care about putting an RPC for each and every port i/o + <youpi> because hardware is slow anyway + <ArneBab> jupp + <ArneBab> but it is important to see that in real life |