Merge remote-tracking branch 'fp/master'

4 files changed, 127 insertions, 0 deletions

diff --git a/hurd/libdiskfs.mdwn b/hurd/libdiskfs.mdwn
new file mode 100644
index 00000000..dd499785
--- /dev/null
+++ b/hurd/libdiskfs.mdwn
@@ -0,0 +1,42 @@
+[[!meta copyright="Copyright © 2011 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]]."]]"""]]
+
+
+# Paging
+
+In the course of Maksym's [[translator/tmpfs]] work:
+
+IRC, freenode, #hurd, 2011-10-24:
+
+    <mcsim> I've compared the way pagers are handled in ext2fs and found out
+      that for every file new pager is created when occurs reading or writing
+      to this file. Is it necessary? And can one pager handle several memory
+      objects?
+    <antrik> mcsim: yes, this in necessary. one pager port corresponds to one
+      memory object
+    <antrik> mcsim: note that a pager, from the kernel's point of view, is
+      essentially just the port used to communicated with the process
+      responsible for paging the object. how your process manages multiple
+      pager ports is up to you
+    <mcsim> so, how can I attach those pager_* functions, which are declared
+      now in pager-stubs.c to new pager?
+    <mcsim> or is it done automatically with all pagers, which I create, If
+      only I'm not using default one?
+    <antrik> I'm not sure how libpager works; but I suspect it's based on
+      libports. you probably need a port class for the pager ports, and add the
+      port for each new pager your create to that class
+    <antrik> (of course you also need to add it to some port bucket. if you use
+      a single dispatcher for everything, this would be the default bucket; if
+      you want a separate thread for pager handling, you'd have to create an
+      extra bucket for the pagers)
+
+This is the `diskfs_get_filemap` function that a `libdiskfs` client has to
+provide; used in `libdiskfs/rdwr-internal.c:_diskfs_rdwr_internal`, which in
+turn is used by the [[interface/io_read]]/[[interface/io_write]] RPCs.
diff --git a/hurd/libstore/examples/ramdisk/discussion.mdwn b/hurd/libstore/examples/ramdisk/discussion.mdwn
new file mode 100644
index 00000000..d73bf903
--- /dev/null
+++ b/hurd/libstore/examples/ramdisk/discussion.mdwn
@@ -0,0 +1,72 @@
+[[!meta copyright="Copyright © 2011 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]]."]]"""]]
+
+[[!tag open_issue_hurd]]
+
+
+# IRC, freenode, #hurd, 2011-10-15
+
+    <antrik> youpi: I'm not at all talking about ordinary tmpfs. I'm talking
+      about the proposed variant using a separate backing store
+    <antrik> youpi: and as you might remember, I once came up with a crazy
+      passive translator command line (based on another crazy passive
+      translator command line from tschwinge) that can automatically do the
+      mkfs
+    <antrik> so there is really very little benefit in using something else
+      than ext2fs when not paging to the swap partition
+    <antrik> real tmpfs IMHO is mostly useful precisely because it uses the
+      ordinary swap, and doesn't have an explicit size limit...
+    <youpi> well, it is still quite a waste to bounce data betwen page cache
+      and memory storage
+    <youpi> or is ext2fs able to map the store data directly?
+    <youpi> then there's only the medata bounce which is spurious
+    <youpi> and still, even a one-liner settrans doesn't fit with the "is just
+      an fs alternative for the existing tmpfs-mounting scripts"
+    <antrik> youpi: well, if the invocation is the major concern, it would be
+      trivial to write a tiny wrapper binary or script that acts like a
+      "normal" FS...
+    <youpi> antrik: could you write it then?
+    <antrik> you mean a shell script that uses ext2fs on a memory store to act
+      like a "proper" tmpfs?
+    <youpi> I mean whatever that permits to just run mount none /tmp -t tmpfs
+    <youpi> and just works already nowadays
+    <youpi> which we could e.g. ship instead of our currently-completely bugged
+      tmpfs
+    <antrik> I suspect the mount script just looks for /hurd/tmpfs in this
+      case? if so, that should indeed be pretty trivial. let's see if I can dig
+      up my crazy command line -- turning that into a "proper" script should be
+      quite easy I hope...
+    <antrik> hm... I digged up
+      http://lists.gnu.org/archive/html/bug-hurd/2007-04/msg00013.html ; but I
+      wonder how much of it is really necessary for a generic pseudo-tmpfs...
+    <antrik> the major complication seems to be the chmod, which I guess we
+      don't need for most use cases...
+    <youpi> I actually don't see why it's inlined there
+    <youpi> doesn't the caller do it if it needs it?
+    <youpi> ah, well, here there is no caller, it's just a passive entry
+    <antrik> is it a problem that this solution needs an extra node for the
+      store?
+    <youpi> yes
+    <youpi> because you need to say where it resides
+    <youpi> and there's no safe place
+    <youpi> since such safe place would typically be a mounted tmpfs
+    <antrik> I feared that much...
+    <antrik> I suspect we could work around this by not attaching the store to
+      any node; but this a) doesn't work in a shell script, and b) is much more
+      involved...
+    <antrik> hm... can we assume /dev/fd to be present? I have a vague crazy
+      idea...
+    <youpi> yes
+    <antrik> I consider hacking settrans so it grows an option which allows
+      passing the port to the translator as an FD, instead of attaching it to
+      any node... this way, we could work with anonymous translators in shell
+      scripts :-)
+    <antrik> (of course that's not less work than just doing the wrapper in
+      C... but it could be useful in other cases)
diff --git a/hurd/running/virtualbox.mdwn b/hurd/running/virtualbox.mdwn
index d9be09f2..f57fcbc3 100644
--- a/hurd/running/virtualbox.mdwn
+++ b/hurd/running/virtualbox.mdwn
@@ -39,3 +39,8 @@ To convert the image you need the VirtualBox package properly installed with a V
 
 If [[QEMU with KVM|qemu]] is not available, VirtualBox reportedly has better
 performance.
+
+IRC, freenode, #hurd, 2011-10-31:
+
+    <youpi> I don't know what virtualbox does with hardware emulation, but
+      gnumach is awfully slow to probe things there
diff --git a/hurd/translator/tmpfs/notes_various.mdwn b/hurd/translator/tmpfs/notes_various.mdwn
index d16210ca..d1c5cf62 100644
--- a/hurd/translator/tmpfs/notes_various.mdwn
+++ b/hurd/translator/tmpfs/notes_various.mdwn
@@ -212,3 +212,11 @@ License|/fdl]]."]]"""]]
     <antrik> seems something more broke in the meantime :-(
     <antrik> ah, right... but I the main problem was some other change
     <antrik> (or maybe it never really worked, not sure anymore)
+
+---
+
+IRC, freenode, #hurd, 2011-10-11:
+
+    <mcsim> There is no patch for "tmpfs crashes on filling an empty file". For
+      second bug there is Zheng Da's patch, but it wasn't applied (at least I
+      didn't found).