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The CBMEM area is a downward-growing memory region used by coreboot to dynamically allocate tagged data structures ("CBMEM entries") that remain resident during boot. This implements a driver which exports access to the CBMEM entries via sysfs under /sys/bus/coreboot/devices/cbmem-<id>. This implementation is quite versatile. Examples of how it could be used are given below: * Tools like util/cbmem from the coreboot tree could use this driver instead of finding CBMEM in /dev/mem directly. Alternatively, firmware developers debugging an issue may find the sysfs interface more ergonomic than the cbmem tool and choose to use it directly. * The crossystem tool, which exposes verified boot variables, can use this driver to read the vboot work buffer. * Tools which read the BIOS SPI flash (e.g., flashrom) can find the flash layout in CBMEM directly, which is significantly faster than searching the flash directly. Write access is provided to all CBMEM regions via /sys/bus/coreboot/devices/cbmem-<id>/mem, as the existing cbmem tooling updates this memory region, and envisioned use cases with crossystem can benefit from updating memory regions. Link: https://issuetracker.google.com/239604743 Cc: Stephen Boyd <swboyd@chromium.org> Cc: Tzung-Bi Shih <tzungbi@kernel.org> Reviewed-by: Guenter Roeck <groeck@chromium.org> Reviewed-by: Julius Werner <jwerner@chromium.org> Tested-by: Jack Rosenthal <jrosenth@chromium.org> Signed-off-by: Jack Rosenthal <jrosenth@chromium.org> Link: https://lore.kernel.org/r/20221104161528.531248-1-jrosenth@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
fs | ||
include | ||
init | ||
io_uring | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
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scripts | ||
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usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
.rustfmt.toml | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
README |
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.