d04b388381
For payloads with UI based on CBGFX, they usually start by calling clear_canvas or clear_screen and then draw the UI elements. However, that makes the screen flicker. A typical solution is to identify and minimize the area to redraw. However for payloads with complicated UI and do not care about latency, an alternative is to enable buffered I/O. The new enable_graphics_buffer() will redirect all graphics I/O into an invisible working buffer. To flush (redraw) the buffer to the real screen, call flush_graphics_buffer(). To stop buffering, call disable_graphics_buffer(). BUG=None TEST=Add the enable, flush and disable calls to payload 'depthcharge', built a firmware and boots into Chrome OS recover UI. No more flickering. The average rendering time on x86 platform is 1.2ms. Change-Id: Id60a2824fd9e164feae16b92b68b003beabea8d3 Signed-off-by: Hung-Te Lin <hungte@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/44654 Reviewed-by: Julius Werner <jwerner@chromium.org> Reviewed-by: Yu-Ping Wu <yupingso@google.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org> |
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.. | ||
arch | ||
bin | ||
configs | ||
crypto | ||
curses | ||
drivers | ||
gdb | ||
include | ||
libc | ||
libcbfs | ||
liblz4 | ||
liblzma | ||
libpci | ||
sample | ||
tests | ||
Doxyfile | ||
Kconfig | ||
LICENSE_GPL | ||
LICENSES | ||
Makefile | ||
Makefile.inc | ||
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.