coreboot/payloads/libpayload
Julius Werner 05a64d2e10 libpayload: Reorder default memcpy, speed up memset and memcmp
The current default memcpy first copies single bytes to align the
amount, then copies the rest as full words. In practice, the start of a
buffer is much more likely to be word-aligned then the end, and aligned
word access are usually more efficient. This patch reorders those
accesses to first copy as many full words as possible and then finish
the rest with byte accesses to optimize this common case.

This fixes a data abort when using USB on ARM without CONFIG_GPL. Due to
some limitations of how DMA memory is set up in coreboot on ARM, it
currently does not support unaligned accesses. (This could be fixed with
a more complicated patch, but it's usually not an issue... unless, of
course, your memcpy happens to be braindead).

Also add word-aligned accesses to memset and memcmp while I'm at it, and
make memcmp's return value standard's compliant.

BUG=chrome-os-partner:24957
TEST=Manual

Change-Id: I2a7bcb35626a05a9a43fcfd99eb958b485d7622a
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/203547
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
2014-06-23 19:31:18 +00:00
..
arch libpayload arm64: Add gdb stub for arm64 2014-06-20 21:41:05 +00:00
bin libpayload: Add support for arm64 in libpayload 2014-06-07 01:28:57 +00:00
configs libpayload rush: Add serial and timer config options to config.rush 2014-06-20 11:14:14 +00:00
crypto libpayload: Change CONFIG_* to CONFIG_LP_* in the kconfig. 2013-08-14 17:05:33 -07:00
curses libpayload: Change CONFIG_* to CONFIG_LP_* in the kconfig. 2013-08-14 17:05:33 -07:00
drivers libpayload: Fix baseaddr access in serial/tegra.c 2014-06-20 11:11:11 +00:00
gdb libpayload: Add remote GDB support 2014-06-11 03:33:56 +00:00
include libpayload arm64: Correct function names for tlb invalidation 2014-06-20 11:11:06 +00:00
libc libpayload: Reorder default memcpy, speed up memset and memcmp 2014-06-23 19:31:18 +00:00
libcbfs libpayload: Fix pointer related casts 2014-05-14 00:25:48 +00:00
liblzma libpayload: Make lzma truncation non-fatal. 2013-08-19 19:04:35 -07:00
libpci libpayload: minor cleanups 2012-04-04 00:40:31 +02:00
sample fix compilation of hello.elf example payload. 2010-08-28 23:23:47 +00:00
tests libpayload: Change CONFIG_X86_SERIAL_CONSOLE to CONFIG_8250_SERIAL_CONSOLE 2013-09-27 14:05:53 +00:00
util libpayload: Add support for arm64 in libpayload 2014-06-07 01:28:57 +00:00
Config.in libpayload: Introduce new Kconfig to explicitly allow GPL code 2014-06-13 20:37:29 +00:00
Doxyfile Run doxygen -u on doxygen configuration files 2010-06-28 10:40:38 +00:00
LICENSE_GPL libpayload: Introduce new Kconfig to explicitly allow GPL code 2014-06-13 20:37:29 +00:00
LICENSES libpayload: Introduce new Kconfig to explicitly allow GPL code 2014-06-13 20:37:29 +00:00
Makefile libpayload: Add support for arm64 in libpayload 2014-06-07 01:28:57 +00:00
Makefile.inc libpayload: Add remote GDB support 2014-06-11 03:33:56 +00:00
README libpayload, superiotool: README: Prepend coreboot/ to path of change directory line 2013-04-04 17:22:15 +02:00

-------------------------------------------------------------------------------
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.