4 files changed, 60 insertions, 20 deletions
diff --git a/microkernel/mach/gnumach/building.mdwn b/microkernel/mach/gnumach/building.mdwn
index aed87046..b23985ac 100644
--- a/microkernel/mach/gnumach/building.mdwn
+++ b/microkernel/mach/gnumach/building.mdwn
@@ -19,16 +19,19 @@ enabled) is around 50 MiB.
 
 ## Getting the Source Code
 
-You can either use the git repository (see <http://git.savannah.gnu.org/git/hurd/>),
+You can either use the git repository (see <https://git.savannah.gnu.org/git/hurd/>),
 
     $ git clone https://git.savannah.gnu.org/git/hurd/gnumach.git/
+    $ cd gnumach
+    $ autoreconf --install
 
-... or get the Debian sources, if you're using Debian. (See
+... or get the Debian sources to build a Debian package, if you're using Debian. (See
 [here](http://packages.debian.net/source/unstable/gnumach).)
 
     $ apt source gnumach
+    $ cd gnumach-XXXXXXXX
 
-## On Debian Systems:
+## Building a `.deb` package on Debian Systems:
 
 ### Preparing for the Build
 
@@ -40,34 +43,29 @@ and some additional dependencies specified by the gnumach source package:
 
 ### Building and Installing ... Debian `.deb` files
 
-Change into the directory with the downloaded / unpacked GNU Mach sources,
+Start the build process with
 
-    $ cd gnumach-XXXXXXXX
+    $ dpkg-buildpackage -us -uc -b
 
-Start the build process with
+But to get it built faster, you probably want to only build the most common uniprocessor variant:
 
-    $ dpkg-buildpackage -us -uc -b -rfakeroot
+    $ dpkg-buildpackage -us -uc -b -Ppkg.gnumach.onlyup
 
 [[GNU_Mach|gnumach]] is now building.  To use the new kernel, you must install the
 resulting `.deb` package which is located one directory above the build
 directory and has a similar name as the build directory:
 
-    # dpkg -i ../gnumach_XXXXXXXX-X_hurd-i386.deb
+    # dpkg -i ../gnumach-image-1.8-486_*_hurd-i386.deb
 
 You can now reboot your computer and enjoy the new kernel.
 
-## On non-Debian Systems:
+## Building from the git repository:
 
 ### Preparing for the Build
 
 Building GNU Mach requires a C compiler, a _static_ 32 bit standard C library,
 your favourite flavor of awk (gawk) and GNU make.
 
-First, create the configuration files:
-
-    $ cd gnumach
-    $ autoreconf --install
-
 GNU Mach (and the associated headers) need be built in a separate build directory:
 
     $ mkdir build
@@ -77,7 +75,7 @@ Run configure:
 
     $ ../configure --prefix=
 
-If building on a 64 bit host system,
+If building on a Linux 64 bit host system,
 you need a number of additional settings to force a 32 bit build:
 
     $ ../configure --prefix= --host=i686-gnu LD=i686-linux-gnu-ld CC=i686-linux-gnu-gcc
diff --git a/microkernel/mach/gnumach/debugging.mdwn b/microkernel/mach/gnumach/debugging.mdwn
index a134b618..bcff970e 100644
--- a/microkernel/mach/gnumach/debugging.mdwn
+++ b/microkernel/mach/gnumach/debugging.mdwn
@@ -73,6 +73,10 @@ and then type continue, to let Mach continue execution. The debugger will be ent
     struct db_watchpoint watch = { .task = NULL, .loaddr= 0x40e, .hiaddr = 0x40e+2, .link = NULL};
     db_set_hw_watchpoint(&watch, 0);
 
+To discover what an arbitrary address points to, try
+
+    whatis  0x123400
+
 # GDB in QEMU
 
 When you're [[running_a_system_in_QEMU|hurd/running/qemu]] you can directly
@@ -128,6 +132,43 @@ working directory. For example:
 
 ## [[open_issues/debugging_gnumach_startup_qemu_gdb]]
 
+## Debug 64-bit gnumach
+
+[[build|microkernel/mach/gnumach/building/]] 64-bit gnumach with:
+
+    $ export CFLAGS=-g
+    $ ../configure --enable-kdb ...
+
+run a spare Hurd vm (prepare for data loss in vm):
+
+* `kvm -net user,hostfwd=tcp:127.0.0.1:2222-:22 -net nic,model=e1000 -drive file=$(echo debian-hurd*.img),cache=writeback -m 1G`
+* `cd gnumach/build`
+* `scp -P 2222 gnumach.gz user@127.0.0.1:/home/user/`
+* You may copy `gnumach.gz` (also create new grub entry) or replace using `mv /home/user/gnumach.gz /boot/gnumach-xxx.gz`
+* Shutdown vm.
+* Append `console=com0` in boot menu and switch to console mode in qemu. (We have known issues with vga output for 64-bit.)
+* You may load only required modules for debugging.
+* `kvm -s -S -net user,hostfwd=tcp:127.0.0.1:2222-:22 -net nic,model=e1000 -drive file=$(echo debian-hurd*.img),cache=writeback -m 1G` (note: `-s -S` added.)
+* `gdb ./gnumach`
+* `(gdb) target remote :1234`
+* Press `c` to continue booting.
+
+
+example `/boot/grub/grub.cfg`:
+
+    multiboot       /boot/gnumach-1.8-486.gz root=part:2:device:hd0 console=com0
+    ...
+    echo            'Loading the Hurd ...'
+    module          /hurd/ext2fs.static ext2fs --readonly \
+                    --multiboot-command-line='${kernel-command-line}' \
+                     \
+                    --host-priv-port='${host-port}' --device-master-port='${device-port}' \
+                    --exec-server-task='${exec-task}' -T typed '${root}' \
+                    '$(fs-task=task-create)' '$(task-resume)'
+    module          /lib/ld.so.1 exec /hurd/exec '$(exec-task=task-create)'
+
+
+
 
 # Code Inside the Kernel
 
diff --git a/microkernel/mach/gnumach/memory_management.mdwn b/microkernel/mach/gnumach/memory_management.mdwn
index 477f0a18..6eca2bce 100644
--- a/microkernel/mach/gnumach/memory_management.mdwn
+++ b/microkernel/mach/gnumach/memory_management.mdwn
@@ -13,6 +13,7 @@ License|/fdl]]."]]"""]]
 
 [[!toc]]
 
+A related page is the [[open_issues/resource_management_problems]].
 
 # IRC, freenode, #hurd, 2011-02-15
 
diff --git a/microkernel/mach/gnumach/projects/mach_5.mdwn b/microkernel/mach/gnumach/projects/mach_5.mdwn
index 7b59170b..d7355f4b 100644
--- a/microkernel/mach/gnumach/projects/mach_5.mdwn
+++ b/microkernel/mach/gnumach/projects/mach_5.mdwn
@@ -54,11 +54,11 @@ rewrite rights and pointers to out-of-band memory, it has to parse the
 message.  As type information and values are interleaved, it has to
 iterate over the whole message.
 
-Furthermore, there are two kinds of type descriptors, mach_msg_type_t
-and mach_msg_type_long_t.  The reason for this is that the amount of
-data that can be described using mach_msg_type_t is just 131072 byte.
-This is because msgt_size is an 8-bit value describing the size of one
-element in bits, and msgt_number is an 12-bit value describing the
+Furthermore, there are two kinds of type descriptors, `mach_msg_type_t`
+and `mach_msg_type_long_t`.  The reason for this is that the amount of
+data that can be described using `mach_msg_type_t` is just 131072 byte.
+This is because `msgt_size` is an 8-bit value describing the size of one
+element in bits, and `msgt_number` is an 12-bit value describing the
 number of items.
 
 ### Required change to the message format