Andrew Wu 1287d1cc80 Makefile: Check $CC variable returned from xcompile is not empty.
If xcompile can't find out suitable GCC compiler for i386/armv7, it
will not set $CC_i386/$CC_armv7 variable. Makefile sets $CC variable
from xcompile, and will print strange error messages when executing
$CC program if $CC is empty.

Add checking to avoid this problem. If $CC is empty, also delete
invalid .xcompile file, so Make can recreate this file next time.

Change-Id: Ia8d481d76ca52f3351cb99f05779d06947161c5d
Signed-off-by: Andrew Wu <arw@dmp.com.tw>
Reviewed-on: http://review.coreboot.org/3905
Tested-by: build bot (Jenkins)
Reviewed-by: Jonathan A. Kollasch <jakllsch@kollasch.net>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
2014-01-23 20:43:28 +01:00
..
2014-01-08 13:24:43 +01:00
2012-04-04 00:40:31 +02:00
2013-11-25 23:36:27 +01:00

-------------------------------------------------------------------------------
libpayload README
-------------------------------------------------------------------------------

libpayload is a minimal library to support standalone payloads
that can be booted with firmware like coreboot. It handles the setup
code, and provides common C library symbols such as malloc() and printf().

Note: This is _not_ a standard library for use with an operating system,
rather it's only useful for coreboot payload development!
See http://coreboot.org for details on coreboot.


Installation
------------

 $ git clone http://review.coreboot.org/p/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

 $ sudo make install (optional, will install into /opt per default)

As libpayload is for 32bit x86 systems only, you might have to install the
32bit libgcc version, otherwise your payloads will fail to compile.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.


Usage
-----

Here's an example of a very simple payload (hello.c) and how to build it:

 #include <libpayload.h>

 int main(void)
 {
     printf("Hello, world!\n");
     return 0;
 }

Building the payload using the 'lpgcc' compiler wrapper:

 $ lpgcc -o hello.elf hello.c

Please see the sample/ directory for details.


Website and Mailing List
------------------------

The main website is http://www.coreboot.org/Libpayload.

For additional information, patches, and discussions, please join the
coreboot mailing list at http://coreboot.org/Mailinglist, where most
libpayload developers are subscribed.


Copyright and License
---------------------

See LICENSES.