lguest: the documentation, example launcher

A brief document describing how to use lguest.  Because lguest doesn't have an
ABI we also include an example launcher in the Documentation directory.

[jmorris@namei.org: Fix up nat example in documentation]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: James Morris <jmorris@namei.org>
Cc: Matias Zabaljauregui <matias.zabaljauregui@cern.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/Documentation/lguest/Makefile b/Documentation/lguest/Makefile
new file mode 100644
index 000000000000..b9b9427376e9
--- /dev/null
+++ b/Documentation/lguest/Makefile
@@ -0,0 +1,27 @@
+# This creates the demonstration utility "lguest" which runs a Linux guest.
+
+# For those people that have a separate object dir, look there for .config
+KBUILD_OUTPUT := ../..
+ifdef O
+  ifeq ("$(origin O)", "command line")
+    KBUILD_OUTPUT := $(O)
+  endif
+endif
+# We rely on CONFIG_PAGE_OFFSET to know where to put lguest binary.
+include $(KBUILD_OUTPUT)/.config
+LGUEST_GUEST_TOP := ($(CONFIG_PAGE_OFFSET) - 0x08000000)
+
+CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 \
+        -static -DLGUEST_GUEST_TOP="$(LGUEST_GUEST_TOP)" -Wl,-T,lguest.lds
+LDLIBS:=-lz
+
+all: lguest.lds lguest
+
+# The linker script on x86 is so complex the only way of creating one
+# which will link our binary in the right place is to mangle the
+# default one.
+lguest.lds:
+        $(LD) --verbose | awk '/^==========/ { PRINT=1; next; } /SIZEOF_HEADERS/ { gsub(/0x[0-9A-F]*/, "$(LGUEST_GUEST_TOP)") } { if (PRINT) print $$0; }' > $@
+
+clean:
+        rm -f lguest.lds lguest