OSv debugging and trace analysis are much better covered in the Wiki
pages.  Replace the text in README with links to the more up-to-date
Wiki.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Our need for "make external" was plagued with problems. First and formost,
it was annoying - people need to be told to run "make all external" instead
of just "make". And as a Vlad recently discovered, it strangely relied on a
debug-mode build to have happened, and also "make clean" doesn't undo what
"make external" did.

"make external" had a glorious past, but today all that was left of it
is 3 measly tests which we compile from external/glibc-testsuite: malloc,
getcwd and clock. These tiny tests - 3 out of 796 tests (!!) in the full
glibc test suite - aren't really important enough to cause all this
"make external" mess. So this patch removes them, and the need for a
"make external".

If we'll ever want to bring back these tests, I think we need to delete the
partial external/glibc-testsuite directory, and bring the *full* glibc
test suite of 796 tests, into a separate module. The glibc test suite can be
downloaded together with the glibc source code - they are all files named
tst-*.c in the glibc source tree.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Add on the top of README.md a short introduction to what OSv is.
If someone gets to our github page, https://github.com/cloudius-systems/osv

,
and scrolls down, it's strange that we only explain how to build OSv,
without first mentioning what it is.

Fixes #148

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

OSv can only be built on a 64-bit Linux distribution - otherwise the
compiler will not (by default, at least) generate 64-bit code, and we
won't be able to run the 64-guest needed for building the ZFS filesystem.

Make this requirement explicit in README.md.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

We were missing the prerequisite qemu-img (needed for qemu-nbd, used
during our build) and of course qemu-system-x86 (we run the guest as
part of the build, to have it write files into the ZFS image).

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Signed-off-by: Juan Antonio Osorio Robles <jaosorior@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

The "debugging" section of README.md was misleading - it suggested
one needs to build with "mode=debug" to debug (usually, you don't),
or that disabling preemption was a good idea for debugging.

Change this to drop the preempt=0 suggestion, and make mode=debug an
option, not a recommendation. Also link to our "Debugging OSv" wiki
page, which is much more informative - and includes very important
information still missing in the README (such as a line one needs to
add to ~/.gdbinit, and how to handle multiple vcpus).

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Fixed a couple of spelling mistakes in README.md

Signed-off-by: Omer Karadagli <ufokaradagli@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

The -j must have been included by mistake, otherwise make uses unlimited
jobs.

Signed-off-by: David Leifker <dlei...@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Default image format stays QCOW2 as before.  May be changed via img_format
variable:

  make img_fomat=raw all

This option is required by release-ec2 script as EC2 does not support QCOW2.
Also will be useful for other hypervisors like VMWARE.

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Switch to Markdown syntax in README. I did the minimal amount of changes
to make the rendering on Github look sane. We can prettify it even more
later.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>