summaryrefslogtreecommitdiff
path: root/eclass/linux-build.eclass
blob: 487fc8b0cc2f3c77b42e9916d53a709d8a5f0224 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
# Copyright 1999-2017 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

# @ECLASS: linux-build.eclass
# @MAINTAINER:
# Bertrand Jacquin <bertrand@jacquin.bzh>
# @BLURB: Eclass for building kernel
# @DESCRIPTION:
# Build kernel properly

case "${EAPI:-0}" in
	7|8)
		;;
	*)	die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}"
		;;
esac

ETYPE="sources"

PYTHON_COMPAT=( python3_{11..13} )

inherit savedconfig llvm python-any-r1 kernel-2
detect_version

EXPORT_FUNCTIONS pkg_pretend pkg_setup src_prepare src_compile src_install pkg_postinst

: ${LINUX_BUILD_MOD_SIG_DAYS:=365}
: ${LINUX_BUILD_MOD_SIG_RSA_KEY_SIZE:=2048}
: ${LINUX_BUILD_MOD_SIG_ECC_KEY_CURVE:=secp384r1}

SLOT="${PV%.*}"

DESCRIPTION="Kernel stable sources and build"
HOMEPAGE="https://www.kernel.org"
SRC_URI="${KERNEL_URI} ${GENPATCHES_URI} ${ARCH_URI}"

SRCDIR="${WORKDIR}/linux-${KV_FULL}"
BUILDDIR="${WORKDIR}/build"

KV_EXTRA="${EXTRAVERSION}"
S="${SRCDIR}"

IUSE="build debug llvm rust source"
REQUIRED_USE="symlink? ( source )
	rust? ( llvm )"

BDEPEND="${BDEPEND}
	app-alternatives/bc
	sys-apps/diffutils
	virtual/libelf
	${PYTHON_DEPS}
	debug? (
		dev-util/pahole
	)
	llvm? (
		sys-devel/clang:=
		sys-devel/llvm:=
		sys-devel/lld:=
	)
	rust? ( !arm? ( !x86? (
		dev-lang/rust:=[rust-src]
		dev-util/bindgen
	) ) )"
DEPEND="${DEPEND}
	sys-apps/kmod"

# @FUNCTION: _linux-build_configval
# @INTERNAL
# @DESCRIPTION:
# Request a CONFIG value from .config file
# Return true if set, and define CONFIG_<key>
# Return false if not set
_linux-build_configval() {
	local _v="CONFIG_$1"

	# Export only the needed config value
	# when not already define
	declare -p "${_v}" > /dev/null 2>&1 \
		|| . <(sed -n "/^${_v}=/ p" "${BUILDDIR}/.config")

	case "${!_v}" in
		"") declare "$_v=n" ; export "${_v}" ; return 1 ;;
		*)                    export "${_v}" ; return 0 ;;
	esac
}

_linux-build_protect() {
	local _dir="${1%/*}"
	local _file="${1##*/}"
	local _path
	local i

	_path="${EPREFIX}/${_dir}/${_file}"
	if [[ ! -e "${_path}" ]] ; then
		echo "${_path}"
		return 0
	fi

	for (( i = 0 ; i < 9999 ; i++ )) ; do
		printf -v _path "${EPREFIX}/${_dir}/._cfg%04d_${_file}" "${i}"

		if [[ ! -e "${_path}" ]] ; then
			echo "${_path}"
			return 0
		fi
	done

	return 1
}

_linux-build_relpath() {
	local _file="${1}"
	local _mnt

	# FIXME find a way to identify path of file relative to mount point
	# when file does not exist yet, neither stat or findmnt support it,
	# until then, use a prefix whitelist
	case "${_file}" in
		/boot/*) _mnt="$(stat -c '%m' /boot)" ;;
		*) die "${FUNCNAME} does not handle ${_file}" ;;
	esac

	echo "${_file/#${_mnt}}"
}

_linux-build_get-portage-versions() {
	local -a _v
	local _rv

	if [[ "${PF}" != "${P}" ]] ; then
		_v+=( "${PF}" )
	fi

	_v+=( "${P}" )

	if [[ -n "${REPLACING_VERSIONS}" ]] ; then
		for _rv in ${REPLACING_VERSIONS} ; do
			_v+=( "${PN}-${_rv}" )
		done
	fi

	_v+=( "${PN}"  )

	echo "${_v[@]}"
}

_linux-build_pkg_setup-build-config() {
	local _v

	if ! use savedconfig ; then
		return 0
	fi

	if [[ -e "${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${PF}" ]] ; then
		ebegin "Restoring configuration from ${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${PF}"
		eend 0
		return 0
	fi

	for _v in $(_linux-build_get-portage-versions) ; do
		ebegin "Checking existence of ${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${_v}"
		if [[ -e "${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${_v}" ]] ; then
			eend 0

			ebegin "Restoring configuration from ${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${_v}"
			cp "${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${_v}" \
				"${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${PF}" \
				|| die "Failed to copy ${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${_v}"

			eend 0
			return 0
		fi

		eend 1
	done

	return 1
}

_linux-build_pkg_setup-build-x509() {
	local _v

	for _v in $(_linux-build_get-portage-versions) ; do
		ebegin "Checking existence of ${PORTAGE_CONFIGROOT%/}/etc/ssl/private/${_v}.pem"
		if [[ -e "${PORTAGE_CONFIGROOT%/}/etc/ssl/private/${_v}.pem" ]] ; then
			eend 0
			mkdir "${T}/certs"

			ebegin "Restoring x509 pair from ${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${_v}"
			cp --preserve=mode,ownership \
				"${PORTAGE_CONFIGROOT%/}/etc/ssl/private/${_v}.pem" "${T}/certs/signing_key.pem" \
				|| die "Failed to copy ${PORTAGE_CONFIGROOT%/}/etc/ssl/private/${_v}.pem"

			eend 0
			return 0
		fi

		eend 1
	done

	return 1
}

_linux-build_pkg_setup-build() {
	_linux-build_pkg_setup-build-config
	_linux-build_pkg_setup-build-x509
}

linux-build_pkg_setup() {
	kernel-2_pkg_setup

	if use build ; then
		use llvm && llvm_pkg_setup
		python-any-r1_pkg_setup
		_linux-build_pkg_setup-build
	fi
}

linux-build_pkg_pretend() {
	if use llvm ; then
		case "${ARCH}" in
			arm|arm64) ;;
			amd64|x86) ;;
			*) die "USE=llvm is not supported by ARCH=${ARCH}" ;;
		esac

		if ver_test -lt 5.10 ; then
			die "USE=llvm is supported starting with ${CATEGORY}/${PN}-5.10"
		fi
	fi
}

_linux-build_src_prepare_build() {
	local i

	mkdir "${BUILDDIR}"
	mkdir "${WORKDIR}/boot"

	if [[ -e "${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${PF}" ]] ; then
		cp "${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${PF}" "${BUILDDIR}/.config" \
			|| die "Failed to copy ${PORTAGE_CONFIGROOT%/}/etc/portage/savedconfig/${CATEGORY}/${PF}"
	else
		ewarn "Generate .config using 'defconfig'"
		emake defconfig "${myopt[@]}"
	fi

	if _linux-build_configval EFI_STUB && ! _linux-build_configval CMDLINE ; then
		ewarn "CONFIG_EFI_STUB=y requires CONFIG_CMDLINE"
	fi

	if _linux-build_configval CMDLINE_BOOL && _linux-build_configval CMDLINE ; then
		einfo "Creating kernel.arg"
		einfo "  CONFIG_CMDLINE='${CONFIG_CMDLINE}'"
		echo "${CONFIG_CMDLINE}" > "${WORKDIR}/boot/kernel.arg"
	fi

	local -a BOOTLOADERS=(
		sys-apps/systemd
			/boot/loader/loader.conf "/boot/loader/entries/${KV_FULL}.conf"
	)

	case "${ARCH}" in
		amd64|x86)
			BOOTLOADERS+=(
				sys-boot/grub:0
					/boot/grub/grub.conf none
				sys-boot/grub:2
					/boot/grub/grub.cfg "/boot/grub/entries/${KV_FULL}.cfg"
				sys-boot/syslinux:0
					/boot/extlinux/syslinux.cfg none
				sys-boot/syslinux:0
					/boot/extlinux/extlinux.conf none
			) ;;
		arm|arm64)
			BOOTLOADERS+=(
				sys-boot/raspberrypi-firmware
					/boot/config.txt none
			) ;;
	esac

	KV_INSTALLED="$(best_version ${CATEGORY}/${PN}:${SLOT})"
	KV_INSTALLED="${KV_INSTALLED/#${CATEGORY}\/${PN}-}${KV_EXTRA}"

	# Generate bootloader configuration
	for (( i = 0 ; i < ${#BOOTLOADERS[@]} ; i += 3 )) ; do
		BOOTLOADER_PKG="${BOOTLOADERS[i]}"
		BOOTLOADER_CONFIG_FILE_MAIN="${BOOTLOADERS[i+1]}"
		BOOTLOADER_CONFIG_FILE_KV="${BOOTLOADERS[i+2]}"

		if ! has_version "${BOOTLOADER_PKG}" ; then
			continue
		fi

		# Handle collision protect
		WORKDIR_BOOTLOADER_CONFIG_FILE_MAIN="$(_linux-build_protect "${BOOTLOADER_CONFIG_FILE_MAIN}")"

		if [[ -n "${KV_INSTALLED}" && -e "${BOOTLOADER_CONFIG_FILE_MAIN}" ]] ; then
			einfo "Updating ${BOOTLOADER_CONFIG_FILE_MAIN}"
			mkdir -p "${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_MAIN%/*}"
			sed -e "s@${KV_INSTALLED}@${KV_FULL}@g" \
				"${BOOTLOADER_CONFIG_FILE_MAIN}" \
				> "${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_MAIN}"

			if diff -q \
				"${BOOTLOADER_CONFIG_FILE_MAIN}" \
				"${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_MAIN}" > /dev/null ; then

				rm "${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_MAIN}"
			fi

			_CONFIG_PROTECT+=( "${BOOTLOADER_CONFIG_FILE_MAIN}" )
		fi

		if [[ "${BOOTLOADER_CONFIG_FILE_KV}" != "none" ]] ; then
			# Handle collision protect
			WORKDIR_BOOTLOADER_CONFIG_FILE_KV="$(_linux-build_protect "${BOOTLOADER_CONFIG_FILE_KV}")"

			einfo "Generating ${BOOTLOADER_CONFIG_FILE_KV}"
			mkdir -p "${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_KV%/*}"

			case "${BOOTLOADER_PKG}" in
				sys-apps/systemd)
					cat > "${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_KV}" <<-EOF
						title Gentoo Linux
						version ${KV_FULL}
						linux $(_linux-build_relpath /boot/${KV_FULL}/kernel.img)
						options ${CONFIG_CMDLINE}
					EOF
					;;
				sys-boot/grub:2)
					cat > "${WORKDIR}/bootloader/${WORKDIR_BOOTLOADER_CONFIG_FILE_KV}" <<-EOF
						menuentry 'Gentoo Linux' --class gentoo --class gnu-linux --class gnu --class os {
						$(echo '  ')linux $(_linux-build_relpath /boot/${KV_FULL}/kernel.img) ${CONFIG_CMDLINE}
						}
					EOF
					;;
				*)
					die "${ECLASS} does not know how to generate bootloader configuration for ${BOOTLOADER_PKG}"
					;;
			esac

			_CONFIG_PROTECT+=( "${BOOTLOADER_CONFIG_FILE_KV}" )
		fi
	done

	if [[ -n "${_CONFIG_PROTECT[@]}" ]] ; then
		echo "CONFIG_PROTECT='${_CONFIG_PROTECT[@]}'" > "${WORKDIR}/env.d_42-${P}"
	fi

	_linux-build_configval MODULES || ewarn "CONFIG_MODULES is not set"
	_linux-build_configval UEVENT_HELPER_PATH \
		&& ewarn "CONFIG_UEVENT_HELPER_PATH should be empty"

	if ! _linux-build_configval DEBUG_INFO_BTF && ! use debug ; then
		ewarn "USE=debug is required for CONFIG_DEBUG_INFO_BTF"
	fi

	_linux-build_configval FHANDLE || ewarn "CONFIG_FHANDLE is needed for >=sys-fs/udev-210"
	_linux-build_configval NET     || ewarn "CONFIG_NET is needed for >=sys-fs/udev-210"

	if _linux-build_configval KERNEL_GZIP ; then
		if ! has_version -b "app-alternatives/gzip" ; then
			die "app-alternatives/gzip is required for CONFIG_KERNEL_GZIP"
		fi
	elif _linux-build_configval KERNEL_BZIP2 ; then
		if ! has_version -b "app-alternatives/bzip2" ; then
			die "app-alternatives/bzip2 is required for CONFIG_KERNEL_BZIP2"
		fi
	elif _linux-build_configval KERNEL_LZMA ; then
		if ! has_version -b "app-arch/lzma" ; then
			die "app-arch/lzma is required for CONFIG_KERNEL_LZMA"
		fi
	elif _linux-build_configval KERNEL_XZ; then
		if ! has_version -b "app-arch/xz-utils" ; then
			die "app-arch/xz-utils is required for CONFIG_KERNEL_XZ"
		fi
	elif _linux-build_configval KERNEL_LZO ; then
		if ! has_version -b "app-arch/lzop" ; then
			die "app-arch/lzop is required for CONFIG_KERNEL_LZO"
		fi
	elif _linux-build_configval KERNEL_LZ4 ; then
		if ! has_version -b "app-arch/lz4" ; then
			die "app-arch/lz4 is required for CONFIG_KERNEL_LZ4"
		fi
	elif _linux-build_configval KERNEL_ZSTD ; then
		if ! has_version -b "app-arch/zstd" ; then
			die "app-arch/zstd is required for CONFIG_KERNEL_ZSTD"
		fi
	fi

	if _linux-build_configval IKHEADERS ; then
		if ! has_version -b "app-alternatives/cpio" ; then
			die "app-alternatives/cpio is required for CONFIG_IKHEADERS"
		fi
	fi

	if _linux-build_configval MODULE_COMPRESS ; then
		if _linux-build_configval MODULE_COMPRESS_GZIP ; then
			if ! has_version -b "app-arch/gzip" ; then
				die "app-arch/gzip is required for CONFIG_MODULE_COMPRESS_GZIP"
			fi
		elif _linux-build_configval MODULE_COMPRESS_XZ ; then
			if ! has_version -b "app-arch/xz-utils" ; then
				die "app-arch/xz-utils is required for CONFIG_MODULE_COMPRESS_XZ"
			fi
		else
			die "CONFIG_MODULE_COMPRESS needs one of ( CONFIG_MODULE_COMPRESS_GZIP CONFIG_MODULE_COMPRESS_XZ )"
		fi
	fi

	if _linux-build_configval MODULE_SIG ; then
		local _OPENSSL_REQ_ALGORITHM
		local _OPENSSL_REQ_PKEYOPT

		if ! has_version -b "dev-libs/openssl" ; then
			die "dev-libs/openssl is required for CONFIG_MODULE_SIG"
		fi

		if ! _linux-build_configval MODULE_SIG_HASH ; then
			die "CONFIG_MODULE_SIG_HASH must be defined when using CONFIG_MODULE_SIG"
		fi

		if _linux-build_configval MODULE_SIG_KEY_TYPE_ECDSA ; then
			_OPENSSL_REQ_ALGORITHM="ec"
			_OPENSSL_REQ_PKEYOPT="ec_paramgen_curve:${LINUX_BUILD_MOD_SIG_ECC_KEY_CURVE}"
		else
			_OPENSSL_REQ_ALGORITHM="rsa"
			_OPENSSL_REQ_PKEYOPT="rsa_keygen_bits:${LINUX_BUILD_MOD_SIG_RSA_KEY_SIZE}"
		fi

		mkdir "${BUILDDIR}/certs"

		if [[ -e "${T}/certs/signing_key.pem" ]] ; then
			touch "${BUILDDIR}/certs/x509.genkey"
			cp --preserve=mode,ownership \
				"${T}/certs/signing_key.pem" "${BUILDDIR}/certs/signing_key.pem"
		else
			einfo "Generating x509 config"
			cat > "${BUILDDIR}/certs/x509.genkey" <<-EOF
				[ req ]
				prompt = no
				distinguished_name = ${PF}_subj
				x509_extensions    = ${PF}_exts

				[ ${PF}_subj ]
				O            = Pants On
				OU           = ${KBUILD_BUILD_HOST:-${HOSTNAME}}
				CN           = ${CATEGORY}/${PF}
				emailAddress = ${KBUILD_BUILD_USER:-${PORTAGE_BUILD_USER}}@${KBUILD_BUILD_HOST:-${HOSTNAME}}"

				[ ${PF}_exts ]
				basicConstraints=critical,CA:FALSE
				keyUsage=digitalSignature
				subjectKeyIdentifier=hash
				authorityKeyIdentifier=keyid
			EOF

			einfo "Generating x509 ${_OPENSSL_REQ_ALGORITHM} pair with ${_OPENSSL_REQ_PKEYOPT} and ${CONFIG_MODULE_SIG_HASH}"
			openssl req -x509 -nodes -batch \
				-days "${LINUX_BUILD_MOD_SIG_DAYS}" \
				-newkey "${_OPENSSL_REQ_ALGORITHM}" \
				-pkeyopt "${_OPENSSL_REQ_PKEYOPT}" \
				"-${CONFIG_MODULE_SIG_HASH}" \
				-outform PEM \
				-config "${BUILDDIR}/certs/x509.genkey" \
				-out    "${BUILDDIR}/certs/signing_key.pem" \
				-keyout "${BUILDDIR}/certs/signing_key.pem" \
				|| die "openssl req fail"
		fi

		openssl x509 -inform PEM -noout \
			-in "${BUILDDIR}/certs/signing_key.pem" \
			-subject
	fi

	if _linux-build_configval WLAN ; then
		if ! has_version net-wireless/wireless-regdb ; then
			ewarn "net-wireless/wireless-regdb is required by CONFIG_WLAN"
		fi

		if ! _linux-build_configval EXTRA_FIRMWARE ; then
			ewarn "CONFIG_WLAN requires CONFIG_EXTRA_FIRMWARE='regulatory.db regulatory.db.p7s'"
		elif ! has regulatory.db ${CONFIG_EXTRA_FIRMWARE} ; then
			ewarn "CONFIG_WLAN requires CONFIG_EXTRA_FIRMWARE='regulatory.db regulatory.db.p7s'"
		elif ! has regulatory.db.p7s ${CONFIG_EXTRA_FIRMWARE} ; then
			ewarn "CONFIG_WLAN requires CONFIG_EXTRA_FIRMWARE='regulatory.db regulatory.db.p7s'"
		fi
	fi

	if _linux-build_configval EXTRA_FIRMWARE_DIR && _linux-build_configval EXTRA_FIRMWARE ; then
		for _fw in ${CONFIG_EXTRA_FIRMWARE} ; do
			_file="${CONFIG_EXTRA_FIRMWARE_DIR}/${_fw}"

			if [[ ! -e "${_file}" ]] ; then
				die "${_file} does not exist"
			fi
		done
	fi

	einfo "Checking configuration file"
	cp -a "${BUILDDIR}/.config" "${BUILDDIR}/.config.old"
	if kernel_is -le 3 5 ; then
		emake oldnoconfig "${myopt[@]}"
	else
		emake olddefconfig "${myopt[@]}"
	fi

	local -a _diff_opts=(
		# Empty lines and comments
		--ignore-matching-lines '^$'
		--ignore-matching-lines '^#'

		# Architecture
		--ignore-matching-lines '^CONFIG_ARCH_SUPPORTS_[A-Z_]*='
		--ignore-matching-lines '^CONFIG_ARCH_HAS_[A-Z_]*='

		# Compiler
		--ignore-matching-lines '^CONFIG_CC_VERSION_TEXT='
		--ignore-matching-lines '^CONFIG_AS_HAS_[A-Z0-9_]*='
		--ignore-matching-lines '^CONFIG_CC_HAS_[A-Z0-9_]*='
		--ignore-matching-lines '^CONFIG_CC_HAVE_[A-Z0-9_]*='
		--ignore-matching-lines '^CONFIG_HAVE_[A-Z_]*_COMPILER='
		--ignore-matching-lines '^CONFIG_AS_VERSION='
		--ignore-matching-lines '^CONFIG_RUST_IS_AVAILABLE='

		# GCC only
		--ignore-matching-lines '^CONFIG_CC_IS_GCC='
		--ignore-matching-lines '^CONFIG_GCC_VERSION='
		--ignore-matching-lines '^CONFIG_GCC_ASM_'
		--ignore-matching-lines '^CONFIG_GCC[0-9]+_'
		--ignore-matching-lines '^CONFIG_AS_IS_GNU='
		--ignore-matching-lines '^CONFIG_LD_IS_BFD='
		--ignore-matching-lines '^CONFIG_LD_VERSION='
		--ignore-matching-lines '^CONFIG_PLUGIN_HOSTCC=' # Removed in v5.7
		--ignore-matching-lines '^CONFIG_GCC_PLUGINS='
		--ignore-matching-lines '^CONFIG_GCC_PLUGIN_[A-Z_]*='
		--ignore-matching-lines '^CONFIG_KASAN_STACK='

		# Clang only
		--ignore-matching-lines '^CONFIG_CC_IS_CLANG='
		--ignore-matching-lines '^CONFIG_CLANG_VERSION='
		--ignore-matching-lines '^CONFIG_AS_IS_LLVM='
		--ignore-matching-lines '^CONFIG_LD_IS_LLD='
		--ignore-matching-lines '^CONFIG_LLD_VERSION='
		--ignore-matching-lines '^CONFIG_TOOLS_SUPPORT_RELR='

		# Various
		--ignore-matching-lines '^CONFIG_PAHOLE_VERSION='
	)

	if ! diff -q "${_diff_opts[@]}" "${BUILDDIR}/.config.old" "${BUILDDIR}/.config" ; then
		eerror "You configuration is not up to date"
		diff -Nu "${_diff_opts[@]}" "${BUILDDIR}/.config.old" "${BUILDDIR}/.config"
		die "Bad configuration"
	fi

	emake prepare "${myopt[@]}"
}

linux-build_src_prepare() {
	kernel-2_src_prepare

	bopt=(
		-C "${SRCDIR}"
		KBUILD_OUTPUT="${BUILDDIR}"
		KCONFIG_CONFIG="${BUILDDIR}/.config"

		KBUILD_BUILD_USER="${KBUILD_BUILD_USER:-${PORTAGE_BUILD_USER}}"
		KBUILD_BUILD_HOST="${KBUILD_BUILD_HOST:-${HOSTNAME}}"
		KBUILD_BUILD_TIMESTAMP="$(date --iso-8601=seconds)"
		KBUILD_BUILD_VERSION="1"
	)

	copt=(
		ARCH="$(tc-arch-kernel)" SUBARCH="$(tc-arch-kernel)"
		CROSS_COMPILE="${CHOST}-"
	)

	if use llvm ; then
		copt+=(
			LLVM=1 LLVM_IAS=1
			HOSTCC="${CBUILD}-clang" HOSTCXX="${CBUILD}-clang++"
			HOSTLD="ld.lld"
			HOSTAR="llvm-ar"
			CC="${CHOST}-clang" CXX="${CHOST}-clang++"
			LD="ld.lld"
			AR="llvm-ar"
			AS="llvm-as" # Removed in v5.7
			NM="llvm-nm"
			OBJCOPY="llvm-objcopy"
			OBJDUMP="llvm-objdump"
			READELF="llvm-readelf"
			STRIP="llvm-strip"
		)
	else
		copt+=(
			HOSTCC="$(tc-getBUILD_CC)" HOSTCXX="$(tc-getBUILD_CXX)"
			HOSTLD="$(tc-getBUILD_LD)"
			HOSTAR="$(tc-getBUILD_AR)"
			CC="$(tc-getCC)" CXX="$(tc-getCXX)"
			LD="$(tc-getLD)"
			AR="$(tc-getAR)"
			AS="$(tc-getAS)" # Removed in v5.7
			NM="$(tc-getNM)"
			OBJCOPY="$(tc-getOBJCOPY)"
			OBJDUMP="$(tc-getOBJDUMP)"
			READELF="$(tc-getREADELF)"
			STRIP="$(tc-getSTRIP)"
		)
	fi

	if use rust ; then
		copt+=(
			HOSTRUSTC=rustc
			RUSTC=rustc
			BINDGEN=bindgen
		)
	fi

	copt+=(
		PKG_CONFIG="$(tc-getPKG_CONFIG)"
		PYTHON3="${PYTHON}"
	)

	vopt=(
		EXTRAVERSION="${KV_EXTRA}"
		LOCALVERSION= CONFIG_LOCALVERSION=
		V=1
	)

	myopt=( "${bopt[@]}" "${copt[@]}" "${vopt[@]}" )

	use build && _linux-build_src_prepare_build
}

_linux-build_src_compile_build() {
	einfo "Building kernel"
	emake "${myopt[@]}"
}

linux-build_src_compile() {
	use build && _linux-build_src_compile_build
}

_linux-build_src_install_sources() {
	kernel-2_src_install

	insinto "/usr/src/linux-${KV_FULL}"
	doins "${BUILDDIR}/.config"
}

_linux-build_src_install_build() {
	einfo "Installing kernel"
	emake install "${myopt[@]}" \
		INSTALLKERNEL=../bin/true \
		INSTALL_PATH="${WORKDIR}/boot"

	if _linux-build_configval ARM ||
		_linux-build_configval ARM64 ||
		_linux-build_configval MIPS ; then

		emake dtbs_install "${myopt[@]}" \
			INSTALL_DTBS_PATH="${WORKDIR}/dts"
	fi

	insinto "/boot/${KV_FULL}"
	newins "${BUILDDIR}/.config"    kernel.cfg
	newins "${BUILDDIR}/System.map" System.map

	case "$(tc-arch-kernel)" in
		x86) newins "${BUILDDIR}/arch/$(tc-arch-kernel)/boot/bzImage" kernel.img ;;
		arm|arm64) newins "${BUILDDIR}/arch/$(tc-arch-kernel)/boot/Image" kernel.img ;;
	esac

	if _linux-build_configval EFI_STUB ; then
		insinto "/boot/EFI/linux"

		case "$(tc-arch-kernel)" in
			x86) newins "${BUILDDIR}/arch/$(tc-arch-kernel)/boot/bzImage" "${KV_FULL}.efi" ;;
			arm|arm64) newins "${BUILDDIR}/arch/$(tc-arch-kernel)/boot/Image" "${KV_FULL}.efi" ;;
		esac
	fi

	if _linux-build_configval CMDLINE_BOOL && _linux-build_configval CMDLINE ; then
		insinto "/boot/${KV_FULL}"
		doins "${WORKDIR}/boot/kernel.arg"
	fi

	if _linux-build_configval MODULES ; then
		einfo "Installing modules"
		emake modules_install "${myopt[@]}" \
			INSTALL_MOD_PATH="${WORKDIR}" \
			INSTALL_MOD_STRIP="${PORTAGE_STRIP_FLAGS}"

		einfo "Generating modules.dep"
		depmod -ae -F "${BUILDDIR}/System.map" -b "${WORKDIR}" "${KV_FULL}" \
			|| die "depmod failed"

		rm "${WORKDIR}/lib/modules/${KV_FULL}/build"
		rm "${WORKDIR}/lib/modules/${KV_FULL}/source"

		insinto /lib
		doins -r "${WORKDIR}/lib/modules"
	fi

	if [[ -e "${WORKDIR}/lib/firmware" ]] ; then
		einfo "Installing firmwares"

		insinto /lib
		doins -r "${WORKDIR}/lib/firmware"
	fi

	if [[ -d "${WORKDIR}/dts" ]] ; then
		einfo "Installing device tree"

		while read ; do
			case "${REPLY}" in
				overlays)
					insinto /boot
					doins -r "${WORKDIR}/dts/${REPLY}"
					;;
				broadcom)
					insinto /boot
					doins -r "${WORKDIR}/dts/${REPLY}/."
					;;
				*)
					ewarn "device tree ${REPLY} is not known, installing in default location"
					insinto /boot
					doins -r "${WORKDIR}/dts/${REPLY}"
					;;
			esac
		done < <(
			find "${WORKDIR}/dts" -mindepth 1 -maxdepth 1 -type d -printf '%P\n'
		)
	fi

	if [[ -d "${WORKDIR}/bootloader/boot" ]] ; then
		insinto /boot
		doins -r "${WORKDIR}/bootloader/boot/."

		insinto /etc/env.d
		newins "${WORKDIR}/env.d_42-${P}" "42-${P}"
	fi

	use savedconfig && save_config "${BUILDDIR}/.config"
}

linux-build_src_install() {
	use build  && _linux-build_src_install_build
	use source && _linux-build_src_install_sources
}

linux-build_pkg_postinst() {
	kernel-2_pkg_postinst

	# FIXME https://github.com/gentoo/gentoo/pull/13031
	if ! use symlink && [[ -e "${EROOT}usr/src/linux" ]] ; then
		rm -rf "${EROOT}usr/src/linux"
	fi

	einfo "You may need to:"
	einfo "  make menuconfig ${copt[@]}"
}