coreboot-kgpe-d16

History

Julius Werner 540a98001d printf: Automatically prefix %p with 0x According to the POSIX standard, %p is supposed to print a pointer "as if by %#x", meaning the "0x" prefix should automatically be prepended. All other implementations out there (glibc, Linux, even libpayload) do this, so we should make coreboot match. This patch changes vtxprintf() accordingly and removes any explicit instances of "0x%p" from existing format strings. How to handle zero padding is less clear: the official POSIX definition above technically says there should be no automatic zero padding, but in practice most other implementations seem to do it and I assume most programmers would prefer it. The way chosen here is to always zero-pad to 32 bits, even on a 64-bit system. The rationale for this is that even on 64-bit systems, coreboot always avoids using any memory above 4GB for itself, so in practice all pointers should fit in that range and padding everything to 64 bits would just hurt readability. Padding it this way also helps pointers that do exceed 4GB (e.g. prints from MMU config on some arm64 systems) stand out better from the others. Change-Id: I0171b52f7288abb40e3fc3c8b874aee14b9bdcd6 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/37626 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com> Reviewed-by: David Guckian		2019-12-11 11:38:59 +00:00
..
arch	printf: Automatically prefix %p with 0x	2019-12-11 11:38:59 +00:00
bin	Remove MIPS architecture	2019-11-20 10:10:48 +00:00
configs	trogdor: libpayload USB support	2019-12-05 17:57:31 +00:00
crypto	payloads: Replace all IS_ENABLED(CONFIG_XXX) with CONFIG(XXX)	2019-03-07 17:15:30 +00:00
curses	libpayload: Enable -Wimplicit-fallthrough	2019-07-21 17:17:42 +00:00
drivers	Change all clrsetbits_leXX() to clrsetbitsXX()	2019-12-04 14:11:17 +00:00
gdb	libpayload: gdb: Factor out gdb_handle_reentrant_exception() from arm32	2018-10-12 20:17:40 +00:00
include	endian: Replace explicit byte swapping with compiler builtin	2019-12-06 15:08:50 +00:00
libc	lib/coreboot_table: Add CBMEM_ID_VBOOT_WORKBUF pointer to coreboot table	2019-12-02 13:00:45 +00:00
libcbfs	printf: Automatically prefix %p with 0x	2019-12-11 11:38:59 +00:00
liblz4	Rename __attribute__((packed)) --> __packed	2017-07-13 19:45:59 +00:00
liblzma	libpayload: lzma: Allocate scratchpad on the heap	2016-08-08 19:02:07 +02:00
libpci	libpayload: Add pci_free_dev() and some boilerplate	2017-12-07 21:51:24 +00:00
sample	Remove MIPS architecture	2019-11-20 10:10:48 +00:00
tests
Doxyfile	payloads: Remove/fix trailing whitespace	2018-09-04 12:38:40 +00:00
Kconfig	Remove MIPS architecture	2019-11-20 10:10:48 +00:00
LICENSE_GPL
LICENSES
Makefile	Remove MIPS architecture	2019-11-20 10:10:48 +00:00
Makefile.inc	Remove MIPS architecture	2019-11-20 10:10:48 +00:00
README	payloads/libpayload: Update a Makefile for sample libpayload	2019-06-21 09:16:36 +00:00

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 https://www.coreboot.org for details on coreboot.


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

 $ git clone https://review.coreboot.org/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

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

On x86 systems, libpayload will always be 32-bit even if your host OS runs
in 64-bit, so you might have to install the 32-bit libgcc version.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.

Run 'make distclean' before switching boards. This command will remove
your current .config file, so you need 'make menuconfig' again or
'make defconfig' in order to set up configuration. Default configuration
is based on 'configs/defconfig'. See the configs/ directory for examples
of configuration.


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 https://www.coreboot.org/Libpayload.

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


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

See LICENSES.