Merge branch 'master' into external_pager_mechanism

Conflicts:
	microkernel/mach/external_pager_mechanism.mdwn

2 files changed, 90 insertions, 0 deletions

diff --git a/hurd/debugging/translator/capturing_stdout_and_stderr.mdwn b/hurd/debugging/translator/capturing_stdout_and_stderr.mdwn
new file mode 100644
index 00000000..b7cfc3c9
--- /dev/null
+++ b/hurd/debugging/translator/capturing_stdout_and_stderr.mdwn
@@ -0,0 +1,37 @@
+[[!meta copyright="Copyright © 2008, 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]]."]]"""]]
+
+Sometimes it may already be helpful to capture a translator's `stdout` and
+`stderr`, for example in this situation where [[translator/pfinet]] was
+silently dying all the time, without any console output:
+
+    $ sudo settrans -fgap ↩
+      /servers/socket/2 ↩
+      /bin/sh -c '/hurd/pfinet -i eth0 -a [...] > /tmp/stdout 2> /tmp/stderr'
+    $ [...]
+    $ cat /tmp/stdout
+    NET4: Linux TCP/IP 1.0 for NET4.0
+    IP Protocols: ICMP, UDP, TCP
+    TCP: Hash tables configured (ehash 65536 bhash 65536)
+    $ cat /tmp/stderr
+    pfinet: ../../hurd.work/pfinet/ethernet.c:196: ethernet_xmit: Unexpected error: (os/device) invalid IO size.
+
+(Trying to run [[GDB]] in this case was of no help -- due to a bug in GDB
+(supposedly) it wouldn't catch the fault.)
+
+Be made aware that both `stdout` and `stderr` will be block bufferend and no
+longer line buffered when doing such a redirection, so you'll have to arrange
+for appropriate `fflush`es on these, or force them to be line buffered again
+using the appropriate glibc magic (`setvbuf`).  Otherwise you'll see text in
+the output files only if either glibc herself decides to flush (after some KiB
+of text) the after translator exits.
+
+There is also a [[related open issue|open_issues/translator_stdout_stderr]].
diff --git a/hurd/debugging/translator/gdb.mdwn b/hurd/debugging/translator/gdb.mdwn
new file mode 100644
index 00000000..82a50736
--- /dev/null
+++ b/hurd/debugging/translator/gdb.mdwn
@@ -0,0 +1,53 @@
+[[!meta copyright="Copyright © 2007, 2008 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]]."]]"""]]
+
+Say you want to try running file system server ([[`ext2fs`|translator/ext2fs]],
+[[`jfs`|translator/jfs]], ...) against a modified version of
+[[`libpager`|libpager]] and debug the latter one using [[debugging/GDB]].
+
+Set the [[hurd/translator]] like this:
+
+    $ settrans -fgap ↩
+      jfs.img.i ↩
+      /usr/bin/env ↩
+        LD_LIBRARY_PATH=~tschwinge/tmp/hurd/hurd.ogi/build/libpager ↩
+      "$PWD"/jfs.obj/jfs ↩
+        "$PWD"/jfs.img
+
+Then, when starting GDB, start it like this (or use an equivalent method, of
+course):
+
+    $ LD_LIBRARY_PATH=~tschwinge/tmp/hurd/hurd.ogi/build/libpager ↩
+      gdb ↩
+        ~tschwinge/tmp/jfs/jfs.obj/jfs 15436
+    GNU gdb 6.5-debian
+    [...]
+    Reading symbols from /lib/libdiskfs.so.0.3...Reading symbols from /lib/debug/lib/libdiskfs.so.0.3...done.
+    done.
+    Loaded symbols for /lib/libdiskfs.so.0.3
+    Reading symbols from /devel4/tschwinge/tmp/hurd/hurd.ogi/build/libpager/libpager.so.0.3...done.
+    Loaded symbols for /devel4/tschwinge/tmp/hurd/hurd.ogi/build/libpager/libpager.so.0.3
+    Reading symbols from /lib/libstore.so.0.3...Reading symbols from /lib/debug/lib/libstore.so.0.3...done.
+    done.
+    Loaded symbols for /lib/libstore.so.0.3
+    [...]
+    (gdb) break pager_demuxer
+    Breakpoint 1 at 0x105c98d: file ../../libpager/demuxer.c, line 27.
+    [...]
+    Breakpoint 1, pager_demuxer (inp=0x12bded0, outp=0x12bbec0) at ../../libpager/demuxer.c:27
+    27      {
+    (gdb) list
+    22      /* Demultiplex a single message directed at a pager port; INP is the
+    23         message received; fill OUTP with the reply.  */
+    24      int
+    25      pager_demuxer (mach_msg_header_t *inp,
+    [...]
+
+Voilà.