U-Boot machine/arch independent API for external apps
=====================================================
1. Main assumptions
- there is a single entry point (syscall) to the API
- per current design the syscall is a C-callable function in the U-Boot
text, which might evolve into a real syscall using machine exception trap
once this initial version proves functional
- the consumer app is responsible for producing appropriate context (call
number and arguments)
- upon entry, the syscall dispatches the call to other (existing) U-Boot
functional areas like networking or storage operations
- consumer application will recognize the API is available by searching
a specified (assumed by convention) range of address space for the
signature
- the U-Boot integral part of the API is meant to be thin and non-intrusive,
leaving as much processing as possible on the consumer application side,
for example it doesn't keep states, but relies on hints from the app and
so on
- optional (CONFIG_API)
2. Calls
- console related (getc, putc, tstc etc.)
- system (reset, platform info)
- time (delay, current)
- env vars (enumerate all, get, set)
- devices (enumerate all, open, close, read, write); currently two classes
of devices are recognized and supported: network and storage (ide, scsi,
usb etc.)
3. Structure overview
- core API, integral part of U-Boot, mandatory
- implements the single entry point (mimics UNIX syscall)
- glue
- entry point at the consumer side, allows to make syscall, mandatory
part
- helper conveniency wrappers so that consumer app does not have to use
the syscall directly, but in a more friendly manner (a la libc calls),
optional part
- consumer application
- calls directly, or leverages the provided glue mid-layer
Forked from
KED Software Projects / Miscellaneous / KED U-Boot Fork
47206 commits behind the upstream repository.
fuz@fuz.su
authored
Good evening,
I am trying to port FreeBSD to the ASUS Tinker Board, a computer based
on the Rockchip 3288 SoC. FreeBSD's boot loader (named loader(8)) needs
CONFIG_API to be enabled, but trying to build an U-Boot from trunk with
both CONFIG_API and CONFIG_BLK (as required for Rockchip SoC's?) leads
to the following build failure:
$ CROSS_COMPILE=arm-none-eabi- gmake tinker-rk3288_defconfig all
...
CC api/api_storage.o
api/api_storage.c: In function 'dev_read_stor':
api/api_storage.c:334:9: error: 'struct blk_desc' has no member named 'block_read'
if ((dd->block_read) == NULL) {
^~
api/api_storage.c:339:11: error: 'struct blk_desc' has no member named 'block_read'
return dd->block_read(dd, start, len, buf);
^~
api/api_storage.c:340:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
gmake[2]: *** [scripts/Makefile.build:281: api/api_storage.o] Fehler 1
gmake[1]: *** [Makefile:1229: api] Fehler 2
gmake: *** [Makefile:460: __build_one_by_one] Error 2
I applied the following fix, but the product doesn't boot. Perhaps
that's not a property of the fix though:
Yours,
Robert Clausecker| Name | Last commit | Last update |
|---|---|---|
| .. | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| api.c | ||
| api_display.c | ||
| api_net.c | ||
| api_platform-arm.c | ||
| api_platform-mips.c | ||
| api_platform-powerpc.c | ||
| api_private.h | ||
| api_storage.c | ||