2296479dfd
The libpayload CBFS APIs are pretty old and clunky, primarily because of the way the cbfs_media struct may or may not be passed in and may be initialized inside the API calls in a way that cannot be passed back out again. Due to this, the only real CBFS access function we have always reads a whole file with all metadata, and everything else has to build on top of that. This makes certain tasks like reading just a file attribute very inefficient on non-memory-mapped platforms (because you always have to map the whole file). This patch isn't going to fix the world, but will allow a bit more flexibility by bolting a new API on top which uses a struct cbfs_handle to represent a found but not yet read file. A cbfs_handle contains a copy of the cbfs_media needed to read the file, so it can be kept and passed around to read individual parts of it after the initial lookup. The existing (non-media) legacy API is retained for backwards compatibility, as is cbfs_file_get_contents() (which is most likely what more recent payloads would have used, and also a good convenience wrapper for the most simple use case), but they are now implemented on top of the new API. TEST=Booted Oak, made sure that firmware screens and software sync worked okay. Change-Id: I269f3979e77ae691ee9d4e1ab564eff6d45b7cbe Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/14810 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin <adurbin@chromium.org> |
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.. | ||
arch | ||
bin | ||
configs | ||
crypto | ||
curses | ||
drivers | ||
gdb | ||
include | ||
libc | ||
libcbfs | ||
liblz4 | ||
liblzma | ||
libpci | ||
sample | ||
tests | ||
Doxyfile | ||
Kconfig | ||
LICENSES | ||
LICENSE_GPL | ||
Makefile | ||
Makefile.inc | ||
README |
README
------------------------------------------------------------------------------- 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.