Merge branch 'master' of flubber:~hurd-web/hurd-web

5 files changed, 158 insertions, 36 deletions

diff --git a/community/gsoc/project_ideas.mdwn b/community/gsoc/project_ideas.mdwn
index 2046db9e..ca10c8a2 100644
--- a/community/gsoc/project_ideas.mdwn
+++ b/community/gsoc/project_ideas.mdwn
@@ -101,7 +101,8 @@ See also the list of [Hurd-related X.org project ideas](http://wiki.x.org/wiki/H
 [[!inline pages="community/gsoc/project_ideas/gnat" show=0 feeds=no actions=yes]]
 [[!inline pages="community/gsoc/project_ideas/hardware_libs" show=0 feeds=no actions=yes]]
 [[!inline pages="community/gsoc/project_ideas/cdparanoia" show=0 feeds=no actions=yes]]
-[[!inline pages="community/gsoc/project_ideas/perl" show=0 feeds=no actions=yes]]
+[[!inline pages="community/gsoc/project_ideas/perl_python" show=0 feeds=no actions=yes]]
+[[!inline pages="community/gsoc/project_ideas/testsuites" show=0 feeds=no actions=yes]]
 [[!inline pages="community/gsoc/project_ideas/libcap" show=0 feeds=no actions=yes]]
 [[!inline pages="community/gsoc/project_ideas/xattr" show=0 feeds=no actions=yes]]
 [[!inline pages="community/gsoc/project_ideas/valgrind" show=0 feeds=no actions=yes]]
diff --git a/community/gsoc/project_ideas/perl.mdwn b/community/gsoc/project_ideas/perl.mdwn
deleted file mode 100644
index bfe1968e..00000000
--- a/community/gsoc/project_ideas/perl.mdwn
+++ /dev/null
@@ -1,30 +0,0 @@
-[[!meta copyright="Copyright © 2009 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]]."]]"""]]
-
-[[!meta title="Improving Perl Support"]]
-
-Perl is available on the Hurd, but there are quite a lot of test suite
-failures. These could be caused by problems in the system-specific
-implementation bits of Perl, and/or shortcomings in the actual system
-functionality which Perl depends on.
-
-The goal of this project is to fix all of these problems if possible, or at
-least some of them. Some issues might require digging quite deep into Hurd
-internals, while others are probably easy to fix.
-
-Note that while some Perl knowledge is probably necessary to understand what
-the test suite failures are about, the actual work necessary to fix these
-issues is mostly C programming -- in the implementation of Perl and/or the
-Hurd.
-
-Possible mentors: Samuel Thibault (youpi)
-
-Exercise: Make some improvement to Perl support on the Hurd, e.g. fixing one of
-the known test suite failures.
diff --git a/community/gsoc/project_ideas/perl_python.mdwn b/community/gsoc/project_ideas/perl_python.mdwn
new file mode 100644
index 00000000..34e877ab
--- /dev/null
+++ b/community/gsoc/project_ideas/perl_python.mdwn
@@ -0,0 +1,38 @@
+[[!meta copyright="Copyright © 2009, 2010 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]]."]]"""]]
+
+[[!meta title="Improving Perl or Python Support"]]
+
+Perl and Python are available on the Hurd, but there are quite a lot of test suite
+failures. These could be caused by problems in the system-specific
+implementation bits of Perl/Python, and/or shortcomings in the actual system
+functionality which Perl/Python depends on.
+
+The student applying for this project can pick either Perl or Python,
+whichever he is more comfortable with.
+(Perl is higher priority though; and there are more failures too.)
+
+The goal then is to fix all of the problems with the chosen language if possible, or at
+least some of them. Some issues might require digging quite deep into Hurd
+internals, while others are probably easy to fix.
+
+Note that while some Perl/Python knowledge is probably necessary to understand what
+the test suite failures are about, the actual work necessary to fix these
+issues is mostly C programming -- in the implementation of Perl/Python and/or the
+Hurd.
+
+Possible mentors: Samuel Thibault (youpi)
+
+Exercise: Take a stab at one of the testsuite failures,
+and write a minimal testcase exposing the underlying problem.
+Actually fixing it would be a bonus of course --
+but as it's hard to predict which issues will be easy and which will be tricky,
+we will already be satisfied if the student makes a good effort.
+(We hope to see some discussion of the problems in this case though :-) )
diff --git a/community/gsoc/project_ideas/testsuites.mdwn b/community/gsoc/project_ideas/testsuites.mdwn
new file mode 100644
index 00000000..4f8d43fc
--- /dev/null
+++ b/community/gsoc/project_ideas/testsuites.mdwn
@@ -0,0 +1,52 @@
+[[!meta copyright="Copyright © 2010 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]]."]]"""]]
+
+[[!meta title="Fix Compatibility Problems Exposed by Testsuites"]]
+
+A number of software packages come with extensive testsuites.
+Some notable ones are Perl, Python, GNU Coreutils, and glib.
+While these testsuites were written mostly to track regressions in the respective packages,
+some of the tests fail on the Hurd in general.
+
+While in some cases these might point to wrong usage of system interfaces,
+most of the time such failures are actually caused by shortcomings in Hurd's implementation of these interfaces.
+These shortcomings are often not obvious in normal use,
+but can be directly or indirectly responsible for all kinds of failures.
+The testsuites help in isolating such problems,
+so they can be tracked down and fixed.
+
+This task thus consists in running some of the mentioned testsuites
+(and/or any other ones that come to mind),
+and looking into the causes of failures.
+The goal is to analyze all failures in one or more of the listed testsuites,
+to find out what shortcomings in the Hurd implementation cause them (if any),
+and to fix at least some of these shortcomings.
+
+Note that this task somewhat overlaps with the [[Perl/Python task|perl_python]] listed above.
+Here the focus however is not on improving the support for any particular program,
+but on fixing general problems in the Hurd.
+
+This is a very flexible task:
+while less experienced students should be able to tackle at least a few of the easier problems,
+other issues will be challenging even for experienced hackers.
+No specific previous knowledge is required for this task;
+only fairly decent C programming skills.
+While tracking down the various issues,
+the student will be digging into the inner workings of the Hurd,
+and thus gradually gaining the knowledge required for Hurd development in general.
+
+Possible mentors: Samuel Thibault (youpi)
+
+Exercise: Take a stab at one of the testsuite failures,
+and write a minimal testcase exposing the underlying problem.
+Actually fixing it would be a bonus of course --
+but as it's hard to predict which issues will be easy and which will be tricky,
+we will already be satisfied if the student makes a good effort.
+(We hope to see some discussion of the problems in this case though :-) )
diff --git a/community/gsoc/project_ideas/valgrind.mdwn b/community/gsoc/project_ideas/valgrind.mdwn
index 319d33a7..c6fc7459 100644
--- a/community/gsoc/project_ideas/valgrind.mdwn
+++ b/community/gsoc/project_ideas/valgrind.mdwn
@@ -1,4 +1,4 @@
-[[!meta copyright="Copyright © 2009 Free Software Foundation, Inc."]]
+[[!meta copyright="Copyright © 2009, 2010 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
@@ -8,12 +8,73 @@ 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]]."]]"""]]
 
-[[!meta title="Porting valgrind to the Hurd"]]
+[[!meta title="Porting Valgrind to the Hurd"]]
 
-Valgrind is a very powerful tool to debunk bugs. However, in order to do so, it needs deep knowledge of the behavior of kernel traps. In the case of GNU/Hurd, there is a bunch of system calls that GNU Mach handles directly, but also all the MIG RPCs (Remote Procedure Calls) which return their result either inline or through memory allocated by the kernel.
+[Valgrind](http://valgrind.org/) is an extremely useful debugging tool for memory errors.
+(And some other kinds of hard-to-find errors too.)
+Aside from being useful for program development in general,
+a Hurd port will help finding out why certain programs segfault on the Hurd,
+although they work on Linux.
+Even more importantly, it will help finding bugs in the Hurd servers themselfs.
 
-The goal is thus to teach valgrind the exact semantics of all MIG RPCs, most probably in an automatic way from the .defs files.
+To keep track of memory use,
+Valgrind however needs to know how each system call affects the validity of memory regions.
+This knowledge is highly kernel-specific,
+and thus Valgrind needs to be explicitely ported for every system.
 
-As a starter, students can try to teach valgrind a couple of Linux ioctls, as this will make them learn how to use the read/write primitives of valgrind.
+Such a port involves two major steps:
+making Valgrind understand how kernel traps work in general on the system in question;
+and how all the individual kernel calls affect memory.
+The latter step is where most of the work is,
+as the behaviour of each single system call needs to be described.
+
+Compared to Linux,
+Mach (the microkernel used by the Hurd) has very few kernel traps.
+Almost all system calls are implemented as RPCs instead --
+either handled by Mach itself, or by the various Hurd servers.
+All RPCs use a pair of mach\_msg() invocations:
+one to send a request message, and one to receive a reply.
+However, while all RPCs use the same mach\_msg() trap,
+the actual effect of the call varies greatly depending on which RPC is invoked --
+similar to the ioctl() call on Linux.
+Each request thus must be handled individually.
+
+Unlike ioctl(),
+the RPC invocations have explicit type information for the parameters though,
+which can be retrieved from the message header.
+By analyzing the parameters of the RPC reply message,
+Valgrind can know exactly which memory regions are affected by that call,
+even without specific knowledge of the RPC in question.
+Thus implementing a general parser for the reply messages
+will already give Valgrind a fairly good approximation of memory validity --
+without having to specify the exact semantic of each RPC by hand.
+
+While this should make Valgrind quite usable on the Hurd already, it's not perfect:
+some RPCs might return a buffer that is only partially filled with valid data;
+or some reply parameters might be optional,
+and only contain valid data under certain conditions.
+Such specific semantics can't be deduced from the message headers alone.
+Thus for a complete port,
+it will still be necessary to go through the list of all known RPCs,
+and implement special handling in Valgrind for those RPCs that need it.
+
+The goal of this task is at minimum to make Valgrind grok Mach traps,
+and to implement the generic RPC handler.
+Ideally, specific handling for RPCs needing it should also be implemented.
+
+Completing this project will require digging into Valgrind's handling of system calls,
+and into Hurd RPCs.
+It is not an easy task, but a fairly predictable one --
+there shouldn't be any unexpected difficulties,
+and no major design work is necessary.
+It doesn't require any specific previous knowledge:
+only good programming skills in general.
+On the other hand,
+the student will obtain a good understanding of Hurd RPCs while working on this task,
+and thus perfect qualifications for Hurd development in general :-)
 
 Possible mentors: Samuel Thibault (youpi)
+
+Exercise: As a starter,
+students can try to teach valgrind a couple of Linux ioctls,
+as this will make them learn how to use the read/write primitives of valgrind.