MIPS: generic: Allow filtering enabled boards by requirements

Up until now when configuring a generic kernel all board config
fragments have been merged by default unless boards are explicitly
selected by the user specifying BOARDS=.

In many cases this is sub-optimal, since some boards don't make sense to
include in some kernels. For example the MIPS SEAD-3 development board
has only ever been used with 32 bit CPUs, so including support for the
SEAD-3 in a 64 bit kernel is wasteful.

This patch introduces support for specifying requirements in board
config fragments, using comments formatted like so:

  # require CONFIG_BLA=y

For example the SEAD-3 board could specify that it should only be merged
for 32 bit kernels using a requirement line like the following:

  # require CONFIG_32BIT=y

A new generic-board-config.sh script is introduced to handle selecting
the board config fragments to merge & calling merge_config.sh to merge
them. In order to allow requirements to check Kconfig symbols that are
implicitly selected, rather than explicitly specified by
generic_defconfig or one of the ISA config fragments, an intermediate
.config file is saved & used as a reference when checking requirements.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16943/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2017-08-07 16:01:12 -07:00 committed by Ralf Baechle
parent 1ec9dd80be
commit 27e0d4b051
3 changed files with 99 additions and 2 deletions

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@ -8792,6 +8792,7 @@ M: Paul Burton <paul.burton@imgtec.com>
L: linux-mips@linux-mips.org
S: Supported
F: arch/mips/generic/
F: arch/mips/tools/generic-board-config.sh
MIPS/LOONGSON1 ARCHITECTURE
M: Keguang Zhang <keguang.zhang@gmail.com>

View File

@ -500,8 +500,14 @@ $(eval $(call gen_generic_defconfigs,micro32,r2,eb el))
.PHONY: $(generic_defconfigs)
$(generic_defconfigs):
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh \
-m -O $(objtree) $(srctree)/arch/$(ARCH)/configs/generic_defconfig $^ \
$(foreach board,$(BOARDS),$(generic_config_dir)/board-$(board).config)
-m -O $(objtree) $(srctree)/arch/$(ARCH)/configs/generic_defconfig $^ | \
grep -Ev '^#'
$(Q)cp $(KCONFIG_CONFIG) $(objtree)/.config.$@
$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig \
KCONFIG_CONFIG=$(objtree)/.config.$@ >/dev/null
$(Q)$(CONFIG_SHELL) $(srctree)/arch/$(ARCH)/tools/generic-board-config.sh \
$(srctree) $(objtree) $(objtree)/.config.$@ $(KCONFIG_CONFIG) \
"$(origin BOARDS)" $(BOARDS)
$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
#

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@ -0,0 +1,90 @@
#!/bin/sh
#
# Copyright (C) 2017 Imagination Technologies
# Author: Paul Burton <paul.burton@imgtec.com>
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
# This script merges configuration fragments for boards supported by the
# generic MIPS kernel. It checks each for requirements specified using
# formatted comments, and then calls merge_config.sh to merge those
# fragments which have no unmet requirements.
#
# An example of requirements in your board config fragment might be:
#
# # require CONFIG_CPU_MIPS32_R2=y
# # require CONFIG_CPU_LITTLE_ENDIAN=y
#
# This would mean that your board is only included in kernels which are
# configured for little endian MIPS32r2 CPUs, and not for example in kernels
# configured for 64 bit or big endian systems.
#
srctree="$1"
objtree="$2"
ref_cfg="$3"
cfg="$4"
boards_origin="$5"
shift 5
cd "${srctree}"
# Only print Skipping... lines if the user explicitly specified BOARDS=. In the
# general case it only serves to obscure the useful output about what actually
# was included.
case ${boards_origin} in
"command line")
print_skipped=1
;;
environment*)
print_skipped=1
;;
*)
print_skipped=0
;;
esac
for board in $@; do
board_cfg="arch/mips/configs/generic/board-${board}.config"
if [ ! -f "${board_cfg}" ]; then
echo "WARNING: Board config '${board_cfg}' not found"
continue
fi
# For each line beginning with # require, cut out the field following
# it & search for that in the reference config file. If the requirement
# is not found then the subshell will exit with code 1, and we'll
# continue on to the next board.
grep -E '^# require ' "${board_cfg}" | \
cut -d' ' -f 3- | \
while read req; do
case ${req} in
*=y)
# If we require something =y then we check that a line
# containing it is present in the reference config.
grep -Eq "^${req}\$" "${ref_cfg}" && continue
;;
*=n)
# If we require something =n then we just invert that
# check, considering the requirement met if there isn't
# a line containing the value =y in the reference
# config.
grep -Eq "^${req/%=n/=y}\$" "${ref_cfg}" || continue
;;
*)
echo "WARNING: Unhandled requirement '${req}'"
;;
esac
[ ${print_skipped} -eq 1 ] && echo "Skipping ${board_cfg}"
exit 1
done || continue
# Merge this board config fragment into our final config file
./scripts/kconfig/merge_config.sh \
-m -O ${objtree} ${cfg} ${board_cfg} \
| grep -Ev '^(#|Using)'
done