[DistroKit] [PATCH 4/4] v7a: barebox: am335x-mlo: document some unusual kconfig options

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

While we generally prefer ARM-optimized string/memory routines and
support of GPT in barebox, the MLO configuration is special:
It's size constrained by having to run from on-chip SRAM and it need
only worry about loading barebox from the same partition the MLO came
from.

Therefore leave the configuration as-is, but explain the choices made.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 configs/bsp.ref | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/configs/bsp.ref b/configs/bsp.ref
index b7077411c2dd..5b5b4a763b15 100644
--- a/configs/bsp.ref
+++ b/configs/bsp.ref
@@ -45,6 +45,32 @@ optee_disabled_features:
     - CFG_ENABLE_EMBEDDED_TESTS
     - CFG_TEE_CORE_TA_TRACE
 
+barebox_arm_optimized_string_functions:
+  description: |
+    The use of assembler optimized memcpy / memset functions improves
+    throughput at the cost of an increase in binary size.
+    The am335x-mlo configuration is very size constrained, because it
+    needs to fit into on-chip SRAM to be able to set up DRAM and thus
+    we use the smaller C implementation instead.
+  variants:
+    - condition: kconfig.BareboxConfig()['ARCH_OMAP'] and kconfig.BareboxConfig()['SHELL_NONE']
+      value: False
+    - value: True
+
+barebox_gpt_support:
+  description: |
+    The am335x boot ROM expects SD/MMC media to be formatted as MBR
+    and loads the first stage bootloader from the BOOT.BIN file from the
+    first vfat partition. As the MLO
+
+    As the am335x-mlo configuration's only function is to chainload
+    barebox, we only need GPT support later on in the second stage
+    barebox-am335x configuration.
+  variants:
+    - condition: kconfig.BareboxConfig()['ARCH_OMAP'] and kconfig.BareboxConfig()['SHELL_NONE']
+      value: False
+    - value: True
+
 rootfs_unused_libraries:
   description: |
     - libatomic is needed on mips and rpi1 by libcrypto, but for simplicity ship it on all platforms
-- 
2.39.2