Commit 27e0d4b0 authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
Browse files

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: default avatarPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16943/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 1ec9dd80

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -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>

arch/mips/Makefile

+8 −2
Original line number Diff line number Diff line
@@ -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



#

arch/mips/tools/generic-board-config.sh

0 → 100755
+90 −0
Original line number Diff line number Diff line 
#!/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

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