build: move br2 config files to a dedicated directory

README.adoc

@@ -2255,7 +2255,7 @@ Only tested successfully in `x86_64`. Requires <<graphic-mode>>.
 Build and run:
 
 ....
-./build -b br2_x11
+./build -b br2/x11
 ./run -x
 ....
 
@@ -3831,7 +3831,7 @@ Tested on: 93e383902ebcc03d8a7ac0d65961c0e62af9612b
 TODO get working:
 
 ....
-./build -b br2_kmscube
+./build -b br2/kmscube
 ....
 
 build fails with:
@@ -4388,7 +4388,7 @@ where link:http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0190b/
 Then compile with:
 
 ....
-./build -aa -b br2_gpio -c kernel_config_fragment/gpio -l
+./build -aa -b br2/gpio -c kernel_config_fragment/gpio -l
 ....
 
 then test it out with:
@@ -5683,7 +5683,7 @@ before going for the cross compile build.
 Don't forget to explicitly rebuild PARSEC with:
 +
 ....
-./build -a arm -g -b br2_parsec parsec-benchmark-reconfigure
+./build -a arm -B 'BR2_PACKAGE_PARSEC_BENCHMARK=y' -g parsec-benchmark-reconfigure
 ....
 +
 You may also want to test if your patches are still functionally correct inside of QEMU first, which is a faster emulator.
@@ -6178,7 +6178,7 @@ TODO: why is the `--dtb` required despite `fs_bigLITTLE.py` having a DTB generat
 
 We provide the following mechanisms:
 
-* `./build -b data/br2`: append the Buildroot configuration file `data/br2` to a single build. Must be passed every time you run `./build`. The format is the same as link:br2[].
+* `./build -b data/br2`: append the Buildroot configuration file `data/br2` to a single build. Must be passed every time you run `./build`. The format is the same as link:br2/default[].
 * `./build -B 'BR2_SOME_OPTION="myval"'`: append a single option to a single build.
 
 You will then likely want to make those more permanent with: <<retype>>
@@ -6240,7 +6240,7 @@ Save and quit.
 diff -u .config.olg .config
 ....
 
-Then copy and paste the diff additions to link:br2[] to make them permanent.
+Then copy and paste the diff additions to link:br2/default[] to make them permanent.
 
 === Change user
 

build

@@ -10,7 +10,7 @@ kernel_config_fragment_cli_file="${out_dir}/kernel_config_fragment_cli"
 rm -f "$kernel_config_fragment_cli_file"
 touch "$kernel_config_fragment_cli_file"
 configure=true
-config_fragments="${root_dir}/br2"
+config_fragments="${root_dir}/br2/default"
 extra_make_args=
 j="$(nproc)"
 linux_reconfigure=false
@@ -117,7 +117,7 @@ case "$arch" in
     defconfig=qemu_mips64r6_malta_defconfig
   ;;
 esac
-config_fragments="${config_fragments} ${root_dir}/br2_qemu ${br2_cli_file}"
+config_fragments="${config_fragments} ${root_dir}/br2/qemu ${br2_cli_file}"
 
 # Configure.
 if "$configure"; then