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diff --git a/hurd/translator/discussion.mdwn b/hurd/translator/discussion.mdwn index e038ba84..70a6efee 100644 --- a/hurd/translator/discussion.mdwn +++ b/hurd/translator/discussion.mdwn @@ -1,4 +1,5 @@ -[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]] +[[!meta copyright="Copyright © 2011, 2013, 2014 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 @@ -10,7 +11,10 @@ License|/fdl]]."]]"""]] [[!tag open_issue_documentation open_issue_hurd]] -IRC, freenode, #hurd, 2011-08-25: +[[!toc]] + + +# IRC, freenode, #hurd, 2011-08-25 < frhodes> how can I replace an existing running server with a new one without rebooting? @@ -23,3 +27,184 @@ IRC, freenode, #hurd, 2011-08-25: nature < antrik> in some cases, you might even be able simply to remove the old translator... but obviously only for non-critical stuff :-) + + +# IRC, freenode, #hurd, 2013-10-21 + + <braunr> mhmm, there is a problem with thread destruction + +[[open_issues/libpthread/t/fix_have_kernel_resources]]. + + <braunr> actually, translator self destruction + <braunr> if a request arrives after the last thread servicing a port set + returns from mach_msg because of a timeout, but before the translator is + detached from its parent, the client will get an error + <braunr> it should very rarely happen, but if it does, we could face the + same kind of issues we have when a server crashes + <braunr> e.g. sshd looping over select() returning EBADF, consuming all cpu + <braunr> not sure we want to introduce such new issues + + <braunr> i don't think i'll be able to make translators disappear reliably + .. + <braunr> but at least, thread consumption will correctly decrease with + inactivity + + +# IRC, freenode, #hurd, 2014-01-30 + + <sjbalaji> can any one exmplain me hello translator ? I am new to hurd + <teythoon> sjbalaji: sure, what do you want to know ? + <teythoon> how to use it ? + <sjbalaji> No I mean what is the main reason of that translator. I am + familiar with Linux. + <gnu_srs> sjbalaji: start with: + https://www.gnu.org/software/hurd/hurd/documentation/translator_primer.html + <sjbalaji> I ran that example but I am still clueless about the actual + reason behind the translators and this simple hello world translator + example. + <teythoon> sjbalaji: the Hurd is a multiserver os, almost all functionality + lives in userspace servers called 'translators' + <teythoon> sjbalaji: the Hurd uses the file system as namespace to lookup + these servers + <teythoon> e.g. /servers/socket/1 is /hurd/pflocal and handles pipes and + unix socket communication + <sjbalaji> I can see from the example that a hello file is associated with + a /hurd/hello translator + <teythoon> yes + <teythoon> think of translators like FUSE-based filesystems, only more + general + <teythoon> b/c translators are not restricted to provide filesystem-like + services + <sjbalaji> So this example hello translator just adds hello world in the + associated file, am I correct ? + <teythoon> it's not adding stuff to a file + <teythoon> say you did settrans -ac /tmp/hi /hurd/hello, if you do cat + /tmp/hi, cat does some rpc calls to the started /hurd/hello program that + returns 'hello world' as the file contents + <teythoon> in a sense /hurd/hello is a 'filesystem' that provides a single + file + <sjbalaji> So is it like hello is the mount moint for that hello server ? + <teythoon> sjbalaji: yes, kind of that, but in a more general sense + <sjbalaji> teythoon: How can I see the different servers that are running + in the system ? I tried top in the terminal but it returned cannot find + /proc/version + <teythoon> sjbalaji: so it seems your procfs is not running, try as root: + settrans /proc /hurd/procfs -c + <sjbalaji> teythoon: But how does one differentiate between a server and a + normal process ? + <teythoon> one does not + <teythoon> for a rule of thumb: anything from /hurd is a translator + <teythoon> you can view a nodes passive translator record using showtrans, + e.g. showtrans /dev/hd0 + <sjbalaji> Is there something like a man page for translators ? Like how to + work with them or to figure out what services are offered by them ? + <teythoon> well, there is --help + <teythoon> also, go to /dev and /servers and look around using showtrans or + fsysopts + <sjbalaji> teythoon: What is the difference between a nodes active and + passive translator ? + <teythoon> a passive translator record is stored in the file system for the + node + <teythoon> if the node is accessed, and no translator is currently running, + it is started on demand + <teythoon> we call a running translator an active one + <sjbalaji> So the hello translator in the example is a passive one ? + <teythoon> if you used settrans foo /hurd/hello, a node foo is created with + an passive translator record + <teythoon> if you used settrans -a foo /hurd/hello, the translator is + started immediately + <sjbalaji> teythoon: What do you mean by a passive translator record ? + <teythoon> sjbalaji: it's an argv-vector encoded in the filesystem + (currently, only ext2 supports this) + <teythoon> in ext2, it is stored in a block and a os-specific field in the + inode points to that block + <sjbalaji> teythoon: I can't understand the logic behind that :( + <teythoon> this way, the servers are started on demand + <sjbalaji> But once they are invoked they are always online after that. + <teythoon> yes + <sjbalaji> I thought that the server goes down once its used + <gnu_srs> teythoon: shouldn't the passive ones time out if unused? + <teythoon> yes, that's how it was intented to be, but that has been + patched-out in debian/hurd + <gnu_srs> reason? + <teythoon> i don't know the details, but there is a race condition + +(`libports_stability.patch`.) + + +# IRC, freenode, #hurd, 2014-01-31 + + <sjbalaji> How can I see the complete control flow when I run the hello + translator example ? + + +# IRC, freenode, #archhurd, 2014-02-05 + + <CalimeroTeknik> plus I discussed quickly that idea with Richard Stallman + and he told me translators had a conception flaw that would forbid such a + system to be usable + + +## IRC, freenode, #archhurd, 2014-02-06 + + <antrik_> CalimeroTeknik: the "conceptal problem" rms told you about was + probably the simple issue that translators are always followed, even if + they are run by another user + <antrik> CalimeroTeknik: the conceptal problem is only in that the original + designers believed that would be safe, which it isn't. changing that + default policy (to be more like FUSE) wouldn't do much harm to the Hurd's + features, and it should be easy to do + <antrik> it's just nobody bothered so far, because it's not a big deal for + typical use cases + <antrik> rms isn't really in touch with Hurd development. he was made to + believe it was a fundamental issue by a former Hurd developer who got + carried away; and he didn't know enough to realise that it's really not a + big deal at all + + +# Candidates for Google Summer of Code [[community/gsoc/Project_Ideas]] + +## Extend `ls` et al. for Translators + +### IRC, freenode, #hurd, 2014-02-08 + + <youpi> heh + <youpi> I was wondering what that incoming/ directory was in my home + <youpi> ls gave me hundreds of packages + <youpi> then I remembered I had /hurd/httpfs http://incoming.debian.org/ on + it :) + <cluck> if only there were an easy and automated way to make ls and file + managers (like dired!) aware of links, mounts and translators :) + <youpi> cluck: what do you mean by "awaree"? + <cluck> someting like: lrwxrwxrwx 1 foo foo 31 Aug 21 18:01 + my_translator-23.0 -> ../some/fakefs /some_parameters* + <cluck> (yes, i realize it goes against some security practices but maybe + there could be a distinction like with soft/hard links that made it + opaque for some use cases) + + +## Passive Translators + +### IRC, freenode, #hurd, 2014-02-12 + + <braunr> well don't expect rsync to save passive translator records .. + <braunr> i recommend you save either the entire disk image or the partition + <gg0> should i expect it from tar/cp ? + <braunr> no + <braunr> i'm not even sure dumpe2fs does it + <braunr> the only reliable way is to save the block device + <azeem> might be a worthwhile GSOC + <azeem> "implement Hurd specific features in GNU utilities" + <azeem> there were some patches floating around for some things in the past + IIRC + <antrik> azeem: the plan for supporting Hurd features in FS utilities was + exposing them as xattrs, like Roland's Linux patch did... cascardos once + did some work on this, but don't remember how far he got + +[[community/gsoc/project_ideas/xattr]]. + + <antrik> you are right though that it would make for a good GSoC project... + <antrik> of course, *some* utilities would still benefit from explicit Hurd + support -- most notably ls + <azeem> IIRC there were also ls patches at one point + <antrik> can't recall that... but maybe it was befor my time ;-) |