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Message-ID: <3f46aa25-ef45-fff8-dba5-5db1034b38d9@xen0n.name>
Date:   Sun, 1 May 2022 18:09:02 +0800
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Subject: Re: [PATCH V9 05/24] LoongArch: Add build infrastructure
Content-Language: en-US
To:     Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Huacai Chen <chenhuacai@gmail.com>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>
References: <20220430090518.3127980-1-chenhuacai@loongson.cn>
 <20220430090518.3127980-6-chenhuacai@loongson.cn>
From:   WANG Xuerui <kernel@xen0n.name>
In-Reply-To: <20220430090518.3127980-6-chenhuacai@loongson.cn>
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Content-Transfer-Encoding: 7bit
Precedence: bulk


On 4/30/22 17:04, Huacai Chen wrote:
> This patch adds Kbuild, Makefile, Kconfig and link script for LoongArch
> build infrastructure.
>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
>   arch/loongarch/.gitignore              |   9 +
>   arch/loongarch/Kbuild                  |   3 +
>   arch/loongarch/Kconfig                 | 351 +++++++++++++++++++++++++
>   arch/loongarch/Kconfig.debug           |   0
>   arch/loongarch/Makefile                |  99 +++++++
>   arch/loongarch/include/asm/Kbuild      |  29 ++
>   arch/loongarch/include/uapi/asm/Kbuild |   2 +
>   arch/loongarch/kernel/Makefile         |  22 ++
>   arch/loongarch/kernel/vmlinux.lds.S    | 100 +++++++
>   arch/loongarch/lib/Makefile            |   7 +
>   arch/loongarch/mm/Makefile             |   9 +
>   arch/loongarch/pci/Makefile            |   7 +
>   scripts/subarch.include                |   2 +-
>   13 files changed, 639 insertions(+), 1 deletion(-)
>   create mode 100644 arch/loongarch/.gitignore
>   create mode 100644 arch/loongarch/Kbuild
>   create mode 100644 arch/loongarch/Kconfig
>   create mode 100644 arch/loongarch/Kconfig.debug
>   create mode 100644 arch/loongarch/Makefile
>   create mode 100644 arch/loongarch/include/asm/Kbuild
>   create mode 100644 arch/loongarch/include/uapi/asm/Kbuild
>   create mode 100644 arch/loongarch/kernel/Makefile
>   create mode 100644 arch/loongarch/kernel/vmlinux.lds.S
>   create mode 100644 arch/loongarch/lib/Makefile
>   create mode 100644 arch/loongarch/mm/Makefile
>   create mode 100644 arch/loongarch/pci/Makefile
>
> diff --git a/arch/loongarch/.gitignore b/arch/loongarch/.gitignore
> new file mode 100644
> index 000000000000..fd88d21e7172
> --- /dev/null
> +++ b/arch/loongarch/.gitignore
> @@ -0,0 +1,9 @@
> +*.lds
> +*.raw
> +calc_vmlinuz_load_addr
> +elf-entry
> +relocs
> +vmlinux*
> +vmlinuz*
> +
> +!kernel/vmlinux.lds.S
This exclude entry is unnecessary?
> diff --git a/arch/loongarch/Kbuild b/arch/loongarch/Kbuild
> new file mode 100644
> index 000000000000..1ad35aabdd16
> --- /dev/null
> +++ b/arch/loongarch/Kbuild
> @@ -0,0 +1,3 @@
> +obj-y += kernel/
> +obj-y += mm/
> +obj-y += vdso/
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> new file mode 100644
> index 000000000000..44b763046893
> --- /dev/null
> +++ b/arch/loongarch/Kconfig
> @@ -0,0 +1,351 @@
> +# SPDX-License-Identifier: GPL-2.0
> +config LOONGARCH
> +	bool
> +	default y
> +	select ACPI_MCFG if ACPI
> +	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
> +	select ARCH_BINFMT_ELF_STATE
> +	select ARCH_ENABLE_MEMORY_HOTPLUG
> +	select ARCH_ENABLE_MEMORY_HOTREMOVE
> +	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
> +	select ARCH_HAS_PTE_SPECIAL
> +	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> +	select ARCH_INLINE_READ_LOCK if !PREEMPTION
> +	select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPTION
> +	select ARCH_INLINE_READ_LOCK_IRQSAVE if !PREEMPTION
> +	select ARCH_INLINE_READ_UNLOCK if !PREEMPTION
> +	select ARCH_INLINE_READ_UNLOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_READ_UNLOCK_IRQ if !PREEMPTION
> +	select ARCH_INLINE_READ_UNLOCK_IRQRESTORE if !PREEMPTION
> +	select ARCH_INLINE_WRITE_LOCK if !PREEMPTION
> +	select ARCH_INLINE_WRITE_LOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_WRITE_LOCK_IRQ if !PREEMPTION
> +	select ARCH_INLINE_WRITE_LOCK_IRQSAVE if !PREEMPTION
> +	select ARCH_INLINE_WRITE_UNLOCK if !PREEMPTION
> +	select ARCH_INLINE_WRITE_UNLOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_WRITE_UNLOCK_IRQ if !PREEMPTION
> +	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE if !PREEMPTION
> +	select ARCH_INLINE_SPIN_TRYLOCK if !PREEMPTION
> +	select ARCH_INLINE_SPIN_TRYLOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_SPIN_LOCK if !PREEMPTION
> +	select ARCH_INLINE_SPIN_LOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_SPIN_LOCK_IRQ if !PREEMPTION
> +	select ARCH_INLINE_SPIN_LOCK_IRQSAVE if !PREEMPTION
> +	select ARCH_INLINE_SPIN_UNLOCK if !PREEMPTION
> +	select ARCH_INLINE_SPIN_UNLOCK_BH if !PREEMPTION
> +	select ARCH_INLINE_SPIN_UNLOCK_IRQ if !PREEMPTION
> +	select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE if !PREEMPTION
> +	select ARCH_MIGHT_HAVE_PC_PARPORT
> +	select ARCH_MIGHT_HAVE_PC_SERIO
> +	select ARCH_SPARSEMEM_ENABLE
> +	select ARCH_SUPPORTS_ACPI
> +	select ARCH_SUPPORTS_ATOMIC_RMW
> +	select ARCH_SUPPORTS_HUGETLBFS
> +	select ARCH_USE_BUILTIN_BSWAP
> +	select ARCH_USE_CMPXCHG_LOCKREF
> +	select ARCH_USE_QUEUED_RWLOCKS
> +	select ARCH_USE_QUEUED_SPINLOCKS
> +	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> +	select ARCH_WANTS_NO_INSTR
> +	select BUILDTIME_TABLE_SORT
> +	select COMMON_CLK
> +	select GENERIC_CLOCKEVENTS
> +	select GENERIC_CMOS_UPDATE
> +	select GENERIC_CPU_AUTOPROBE
> +	select GENERIC_ENTRY
> +	select GENERIC_FIND_FIRST_BIT
> +	select GENERIC_GETTIMEOFDAY
> +	select GENERIC_IRQ_MULTI_HANDLER
> +	select GENERIC_IRQ_PROBE
> +	select GENERIC_IRQ_SHOW
> +	select GENERIC_LIB_ASHLDI3
> +	select GENERIC_LIB_ASHRDI3
> +	select GENERIC_LIB_CMPDI2
> +	select GENERIC_LIB_LSHRDI3
> +	select GENERIC_LIB_UCMPDI2
> +	select GENERIC_PCI_IOMAP
> +	select GENERIC_SCHED_CLOCK
> +	select GENERIC_TIME_VSYSCALL
> +	select GPIOLIB
> +	select HAVE_ARCH_AUDITSYSCALL
> +	select HAVE_ARCH_COMPILER_H
> +	select HAVE_ARCH_MMAP_RND_BITS if MMU
> +	select HAVE_ARCH_SECCOMP_FILTER
> +	select HAVE_ARCH_TRACEHOOK
> +	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
> +	select HAVE_ASM_MODVERSIONS
> +	select HAVE_CONTEXT_TRACKING
> +	select HAVE_COPY_THREAD_TLS
> +	select HAVE_DEBUG_KMEMLEAK
> +	select HAVE_DEBUG_STACKOVERFLOW
> +	select HAVE_DMA_CONTIGUOUS
> +	select HAVE_EXIT_THREAD
> +	select HAVE_FAST_GUP
> +	select HAVE_GENERIC_VDSO
> +	select HAVE_IOREMAP_PROT
> +	select HAVE_IRQ_EXIT_ON_IRQ_STACK
> +	select HAVE_IRQ_TIME_ACCOUNTING
> +	select HAVE_MEMBLOCK
> +	select HAVE_MEMBLOCK_NODE_MAP
> +	select HAVE_MOD_ARCH_SPECIFIC
> +	select HAVE_NMI
> +	select HAVE_PCI
> +	select HAVE_PERF_EVENTS
> +	select HAVE_REGS_AND_STACK_ACCESS_API
> +	select HAVE_RSEQ
> +	select HAVE_SYSCALL_TRACEPOINTS
> +	select HAVE_TIF_NOHZ
> +	select HAVE_VIRT_CPU_ACCOUNTING_GEN
> +	select IRQ_FORCED_THREADING
> +	select IRQ_LOONGARCH_CPU
> +	select MODULES_USE_ELF_RELA if MODULES
> +	select PCI
> +	select PCI_DOMAINS_GENERIC
> +	select PCI_ECAM if ACPI
> +	select PCI_MSI_ARCH_FALLBACKS
> +	select PERF_USE_VMALLOC
> +	select RTC_LIB
> +	select SPARSE_IRQ
> +	select SYSCTL_EXCEPTION_TRACE
> +	select SWIOTLB
> +	select TRACE_IRQFLAGS_SUPPORT
> +	select ZONE_DMA32
> +
> +config 32BIT
> +	bool
> +
> +config 64BIT
> +	def_bool y
> +
> +config CPU_HAS_FPU
> +	bool
> +	default y
> +
> +config CPU_HAS_PREFETCH
> +	bool
> +	default y
> +
> +config GENERIC_CALIBRATE_DELAY
> +	def_bool y
> +
> +config GENERIC_CSUM
> +	def_bool y
> +
> +config GENERIC_HWEIGHT
> +	def_bool y
> +
> +config L1_CACHE_SHIFT
> +	int
> +	default "6"
> +
> +config LOCKDEP_SUPPORT
> +	bool
> +	default y
> +
> +config MACH_LOONGSON32
> +	def_bool 32BIT
> +
> +config MACH_LOONGSON64
> +	def_bool 64BIT
These two config symbols are not used anywhere in arch/loongarch, but 
from a quick grep it seems they're sharing the names of the MIPS config 
symbols, on purpose, maybe for sharing code between the MIPS-era 
Loongson models and the LoongArch models. If so, a comment explaining 
this could be beneficial.
> +
> +config PAGE_SIZE_4KB
> +	bool
> +
> +config PAGE_SIZE_16KB
> +	bool
> +
> +config PAGE_SIZE_64KB
> +	bool
> +
> +config PGTABLE_2LEVEL
> +	bool
> +
> +config PGTABLE_3LEVEL
> +	bool
> +
> +config PGTABLE_4LEVEL
> +	bool
> +
> +config PGTABLE_LEVELS
> +	int
> +	default 2 if PGTABLE_2LEVEL
> +	default 3 if PGTABLE_3LEVEL
> +	default 4 if PGTABLE_4LEVEL
> +
> +config SCHED_OMIT_FRAME_POINTER
> +	bool
> +	default y
> +
> +menu "Kernel type"
> +
> +source "kernel/Kconfig.hz"
> +
> +choice
> +	prompt "Page Table Layout"
> +	default 16KB_2LEVEL if 32BIT
> +	default 16KB_3LEVEL if 64BIT
> +	help
> +	  Allows choosing the page table layout, which is a combination
> +	  of page size and page table levels. The virtual memory address
> +	  space bits are determined by the page table layout.
"The size of virtual memory address space"?
> +
> +config 4KB_3LEVEL
> +	bool "4KB with 3 levels"
> +	select PAGE_SIZE_4KB
> +	select PGTABLE_3LEVEL
> +	help
> +	  This option selects 4KB page size with 3 level page tables, which
> +	  support a maximum 39 bits of application virtual memory.
"a maximum of XX bits" -- similarly for all occurrences below.
> +
> +config 4KB_4LEVEL
> +	bool "4KB with 4 levels"
> +	select PAGE_SIZE_4KB
> +	select PGTABLE_4LEVEL
> +	help
> +	  This option selects 4KB page size with 4 level page tables, which
> +	  support a maximum 48 bits of application virtual memory.
> +
> +config 16KB_2LEVEL
> +	bool "16KB with 2 levels"
> +	select PAGE_SIZE_16KB
> +	select PGTABLE_2LEVEL
> +	help
> +	  This option selects 16KB page size with 2 level page tables, which
> +	  support a maximum 36 bits of application virtual memory.
> +
> +config 16KB_3LEVEL
> +	bool "16KB with 3 levels"
> +	select PAGE_SIZE_16KB
> +	select PGTABLE_3LEVEL
> +	help
> +	  This option selects 16KB page size with 3 level page tables, which
> +	  support a maximum 47 bits of application virtual memory.
> +
> +config 64KB_2LEVEL
> +	bool "64KB with 2 levels"
> +	select PAGE_SIZE_64KB
> +	select PGTABLE_2LEVEL
> +	help
> +	  This option selects 64KB page size with 2 level page tables, which
> +	  support a maximum 42 bits of application virtual memory.
> +
> +config 64KB_3LEVEL
> +	bool "64KB with 3 levels"
> +	select PAGE_SIZE_64KB
> +	select PGTABLE_3LEVEL
> +	help
> +	  This option selects 64KB page size with 3 level page tables, which
> +	  support a maximum 55 bits of application virtual memory.
> +
> +endchoice
> +
> +config DMI
> +	bool "Enable DMI scanning"
> +	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
> +	default y
> +	help
> +	  Enabled scanning of DMI to identify machine quirks. Say Y
Should be "Enable scanning ..." but the arch/x86 and arch/mips versions 
of this text all have this typo. Might be wise to fix here... then fix 
the other two later.
> +	  here unless you have verified that your setup is not
> +	  affected by entries in the DMI blacklist. Required by PNP
> +	  BIOS code.
Do we have a "PNP BIOS"? I know this is also copied text, but we may 
tweak it to suit our platform.
> +
> +config EFI
> +	bool "EFI runtime service support"
> +	select UCS2_STRING
> +	select EFI_RUNTIME_WRAPPERS
> +	help
> +	  This enables the kernel to use EFI runtime services that are
> +	  available (such as the EFI variable services).
> +
> +	  This option is only useful on systems that have EFI firmware.
> +	  In addition, you should use the latest ELILO loader available
> +	  at <http://elilo.sourceforge.net> in order to take advantage
> +	  of EFI runtime services. However, even with this option, the
Remove mention of ELILO?
> +	  resultant kernel should continue to boot on existing non-EFI
> +	  platforms.
> +
> +config FORCE_MAX_ZONEORDER
> +	int "Maximum zone order"
> +	range 14 64 if PAGE_SIZE_64KB
> +	default "14" if PAGE_SIZE_64KB
> +	range 12 64 if PAGE_SIZE_16KB
> +	default "12" if PAGE_SIZE_16KB
> +	range 11 64
> +	default "11"
> +	help
> +	  The kernel memory allocator divides physically contiguous memory
> +	  blocks into "zones", where each zone is a power of two number of
> +	  pages.  This option selects the largest power of two that the kernel
> +	  keeps in the memory allocator.  If you need to allocate very large
> +	  blocks of physically contiguous memory, then you may need to
> +	  increase this value.
> +
> +	  This config option is actually maximum order plus one. For example,
> +	  a value of 11 means that the largest free memory block is 2^10 pages.
> +
> +	  The page size is not necessarily 4KB.  Keep this in mind
> +	  when choosing a value for this option.
> +
> +config SECCOMP
> +	bool "Enable seccomp to safely compute untrusted bytecode"
> +	depends on PROC_FS
> +	default y
> +	help
> +	  This kernel feature is useful for number crunching applications
> +	  that may need to compute untrusted bytecode during their
> +	  execution. By using pipes or other transports made available to
> +	  the process as file descriptors supporting the read/write
> +	  syscalls, it's possible to isolate those applications in
> +	  their own address space using seccomp. Once seccomp is
> +	  enabled via /proc/<pid>/seccomp, it cannot be disabled
> +	  and the task is only allowed to execute a few safe syscalls
> +	  defined by each seccomp mode.
> +
> +	  If unsure, say Y. Only embedded should say N here.
> +
> +endmenu
> +
> +config ARCH_SELECT_MEMORY_MODEL
> +	def_bool y
> +
> +config ARCH_FLATMEM_ENABLE
> +	def_bool y
> +
> +config ARCH_SPARSEMEM_ENABLE
> +	def_bool y
> +	help
> +	  Say Y to support efficient handling of sparse physical memory,
> +	  for architectures which are either NUMA (Non-Uniform Memory Access)
> +	  or have huge holes in the physical address space for other reasons.
> +	  See <file:Documentation/vm/numa.rst> for more.
> +
> +config ARCH_ENABLE_THP_MIGRATION
> +	def_bool y
> +	depends on TRANSPARENT_HUGEPAGE
> +
> +config ARCH_MEMORY_PROBE
> +	def_bool y
> +	depends on MEMORY_HOTPLUG
> +
> +config MMU
> +	bool
> +	default y
> +
> +config ARCH_MMAP_RND_BITS_MIN
> +	default 12
> +
> +config ARCH_MMAP_RND_BITS_MAX
> +	default 18
> +
> +menu "Bus options"
> +
> +endmenu
> +
> +menu "Power management options"
> +
> +source "drivers/acpi/Kconfig"
> +
> +endmenu
> +
> +source "drivers/firmware/Kconfig"
> diff --git a/arch/loongarch/Kconfig.debug b/arch/loongarch/Kconfig.debug
> new file mode 100644
> index 000000000000..e69de29bb2d1
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> new file mode 100644
> index 000000000000..0a40e79b3265
> --- /dev/null
> +++ b/arch/loongarch/Makefile
> @@ -0,0 +1,99 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Author: Huacai Chen <chenhuacai@loongson.cn>
> +# Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> +
> +#
> +# Select the object file format to substitute into the linker script.
> +#
> +64bit-tool-archpref	= loongarch64
> +32bit-bfd		= elf32-loongarch
> +64bit-bfd		= elf64-loongarch
> +32bit-emul		= elf32loongarch
> +64bit-emul		= elf64loongarch
> +
> +ifdef CONFIG_64BIT
> +tool-archpref		= $(64bit-tool-archpref)
> +UTS_MACHINE		:= loongarch64
> +endif
> +
> +ifneq ($(SUBARCH),$(ARCH))
> +  ifeq ($(CROSS_COMPILE),)
> +    CROSS_COMPILE := $(call cc-cross-prefix, $(tool-archpref)-linux-  $(tool-archpref)-linux-gnu-  $(tool-archpref)-unknown-linux-gnu-)
> +  endif
> +endif
> +
> +cflags-y += $(call cc-option, -mno-check-zero-division)
> +
> +ifdef CONFIG_64BIT
> +ld-emul			= $(64bit-emul)
> +cflags-y		+= -mabi=lp64s
> +endif
> +
> +all-y			:= vmlinux
> +
> +#
> +# GCC uses -G0 -mabicalls -fpic as default.  We don't want PIC in the kernel
> +# code since it only slows down the whole thing.  At some point we might make
> +# use of global pointer optimizations but their use of $r2 conflicts with
> +# the current pointer optimization.
LoongArch doesn't have any notion of "abicalls", please remove the whole 
MIPS legacy... or at least replace with something suitable for LoongArch.
> +#
> +cflags-y			+= -G0 -pipe
> +cflags-y			+= -msoft-float
> +LDFLAGS_vmlinux			+= -G0 -static -n -nostdlib
> +KBUILD_AFLAGS_KERNEL		+= -Wa,-mla-global-with-pcrel
> +KBUILD_CFLAGS_KERNEL		+= -Wa,-mla-global-with-pcrel
> +KBUILD_AFLAGS_MODULE		+= -Wa,-mla-global-with-abs
> +KBUILD_CFLAGS_MODULE		+= -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
These switches are the ones that should receive more love via 
comments... they are here to tell the assembler to emit the "la.global" 
and "la.local" pseudo-insns in a particular "flavor". Why not simply use 
the default? This needs explanation!
> +
> +cflags-y += -ffreestanding
> +cflags-y += $(call as-option,-Wa$(comma)-mno-fix-loongson3-llsc,)
Unfortunately we're still working around the LL/SC hardware issue even 
after migrating to LoongArch... might be better to add a comment too. 
(something along the line of "we work around the issue manually in the 
handwritten assembly, so no automatic workarounds should kick in")
> +
> +load-y		= 0x9000000000200000
> +bootvars-y	= VMLINUX_LOAD_ADDRESS=$(load-y)
> +
> +drivers-$(CONFIG_PCI)		+= arch/loongarch/pci/
> +
> +KBUILD_AFLAGS	+= $(cflags-y)
> +KBUILD_CFLAGS	+= $(cflags-y)
> +KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y)
> +
> +# This is required to get dwarf unwinding tables into .debug_frame
> +# instead of .eh_frame so we don't discard them.
> +KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
> +KBUILD_CFLAGS += -isystem $(shell $(CC) -print-file-name=include)
> +KBUILD_CFLAGS += $(call cc-option,-mstrict-align)
Explain reason of this -mstrict-align request -- it's because not all 
LoongArch cores support unaligned accesses, and as kernel we can't rely 
on others to provide emulation for these accesses.
> +
> +KBUILD_LDFLAGS	+= -m $(ld-emul)
> +
> +ifdef CONFIG_LOONGARCH
> +CHECKFLAGS += $(shell $(CC) $(KBUILD_CFLAGS) -dM -E -x c /dev/null | \
> +	egrep -vw '__GNUC_(MINOR_|PATCHLEVEL_)?_' | \
> +	sed -e "s/^\#define /-D'/" -e "s/ /'='/" -e "s/$$/'/" -e 's/\$$/&&/g')
> +endif
> +
> +head-y := arch/loongarch/kernel/head.o
> +
> +libs-y += arch/loongarch/lib/
> +
> +prepare: vdso_prepare
> +vdso_prepare: prepare0
> +	$(Q)$(MAKE) $(build)=arch/loongarch/vdso include/generated/vdso-offsets.h
> +
> +PHONY += vdso_install
> +vdso_install:
> +	$(Q)$(MAKE) $(build)=arch/loongarch/vdso $@
> +
> +all:	$(all-y)
> +
> +CLEAN_FILES += vmlinux
> +
> +install:
> +	$(Q)install -D -m 755 vmlinux $(INSTALL_PATH)/vmlinux-$(KERNELRELEASE)
> +	$(Q)install -D -m 644 .config $(INSTALL_PATH)/config-$(KERNELRELEASE)
> +	$(Q)install -D -m 644 System.map $(INSTALL_PATH)/System.map-$(KERNELRELEASE)
> +
> +define archhelp
> +	echo '  install              - install kernel into $(INSTALL_PATH)'
> +	echo
> +endef
> diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild
> new file mode 100644
> index 000000000000..a0eed6076c79
> --- /dev/null
> +++ b/arch/loongarch/include/asm/Kbuild
> @@ -0,0 +1,29 @@
> +# SPDX-License-Identifier: GPL-2.0
> +generic-y += dma-contiguous.h
> +generic-y += export.h
> +generic-y += mcs_spinlock.h
> +generic-y += parport.h
> +generic-y += early_ioremap.h
> +generic-y += qrwlock.h
> +generic-y += qspinlock.h
> +generic-y += rwsem.h
> +generic-y += segment.h
> +generic-y += user.h
> +generic-y += stat.h
> +generic-y += fcntl.h
> +generic-y += ioctl.h
> +generic-y += ioctls.h
> +generic-y += mman.h
> +generic-y += msgbuf.h
> +generic-y += sembuf.h
> +generic-y += shmbuf.h
> +generic-y += statfs.h
> +generic-y += socket.h
> +generic-y += sockios.h
> +generic-y += termios.h
> +generic-y += termbits.h
> +generic-y += poll.h
> +generic-y += param.h
> +generic-y += posix_types.h
> +generic-y += resource.h
> +generic-y += kvm_para.h
> diff --git a/arch/loongarch/include/uapi/asm/Kbuild b/arch/loongarch/include/uapi/asm/Kbuild
> new file mode 100644
> index 000000000000..4aa680ca2e5f
> --- /dev/null
> +++ b/arch/loongarch/include/uapi/asm/Kbuild
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +generic-y += kvm_para.h
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> new file mode 100644
> index 000000000000..ead27a11e8e0
> --- /dev/null
> +++ b/arch/loongarch/kernel/Makefile
> @@ -0,0 +1,22 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for the Linux/LoongArch kernel.
> +#
> +
> +extra-y		:= head.o vmlinux.lds
> +
> +obj-y		+= cpu-probe.o cacheinfo.o cmdline.o env.o setup.o entry.o genex.o \
> +		   traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
> +		   elf.o rtc.o syscall.o signal.o time.o topology.o cmpxchg.o \
> +		   inst.o ptrace.o vdso.o
> +
> +obj-$(CONFIG_ACPI)		+= acpi.o
> +obj-$(CONFIG_EFI) 		+= efi.o
> +
> +obj-$(CONFIG_CPU_HAS_FPU)	+= fpu.o
> +
> +obj-$(CONFIG_MODULES)		+= module.o module-sections.o
> +
> +obj-$(CONFIG_PROC_FS)		+= proc.o
> +
> +CPPFLAGS_vmlinux.lds		:= $(KBUILD_CFLAGS)
> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
> new file mode 100644
> index 000000000000..02abfaaa4892
> --- /dev/null
> +++ b/arch/loongarch/kernel/vmlinux.lds.S
> @@ -0,0 +1,100 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <linux/sizes.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/thread_info.h>
> +
> +#define PAGE_SIZE _PAGE_SIZE
> +
> +/*
> + * Put .bss..swapper_pg_dir as the first thing in .bss. This will
> + * ensure that it has .bss alignment (64K).
> + */
> +#define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir)
> +
> +#include <asm-generic/vmlinux.lds.h>
> +
> +OUTPUT_ARCH(loongarch)
> +ENTRY(kernel_entry)
> +PHDRS {
> +	text PT_LOAD FLAGS(7);	/* RWX */
> +	note PT_NOTE FLAGS(4);	/* R__ */
> +}
> +
> +jiffies	 = jiffies_64;
> +
> +SECTIONS
> +{
> +	. = VMLINUX_LOAD_ADDRESS;
> +
> +	_text = .;
> +	.text : {
> +		TEXT_TEXT
> +		SCHED_TEXT
> +		CPUIDLE_TEXT
> +		LOCK_TEXT
> +		KPROBES_TEXT
> +		IRQENTRY_TEXT
> +		SOFTIRQENTRY_TEXT
> +		*(.fixup)
> +		*(.gnu.warning)
> +	} :text = 0
> +	_etext = .;
> +
> +	EXCEPTION_TABLE(16)
> +
> +	. = ALIGN(PAGE_SIZE);
> +	__init_begin = .;
> +	__inittext_begin = .;
> +
> +	INIT_TEXT_SECTION(PAGE_SIZE)
> +	.exit.text : {
> +		EXIT_TEXT
> +	}
> +
> +	__inittext_end = .;
> +
> +	__initdata_begin = .;
> +
> +	INIT_DATA_SECTION(16)
> +	.exit.data : {
> +		EXIT_DATA
> +	}
> +
> +	__initdata_end = .;
> +
> +	__init_end = .;
> +
> +	_sdata = .;
> +	RO_DATA(4096)
> +	RW_DATA(1 << CONFIG_L1_CACHE_SHIFT, PAGE_SIZE, THREAD_SIZE)
> +
> +	.sdata : {
> +		*(.sdata)
> +	}
> +
> +	. = ALIGN(SZ_64K);
> +	_edata =  .;
> +
> +	BSS_SECTION(0, SZ_64K, 8)
> +
> +	_end = .;
> +
> +	STABS_DEBUG
> +	DWARF_DEBUG
> +
> +	.gptab.sdata : {
> +		*(.gptab.data)
> +		*(.gptab.sdata)
> +	}
> +	.gptab.sbss : {
> +		*(.gptab.bss)
> +		*(.gptab.sbss)
> +	}
> +
> +	DISCARDS
> +	/DISCARD/ : {
> +		*(.gnu.attributes)
> +		*(.options)
> +		*(.eh_frame)
> +	}
> +}
> diff --git a/arch/loongarch/lib/Makefile b/arch/loongarch/lib/Makefile
> new file mode 100644
> index 000000000000..7f32f3e4a6ec
> --- /dev/null
> +++ b/arch/loongarch/lib/Makefile
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for LoongArch-specific library files..
One extra period at end of line.
> +#
> +
> +lib-y	+= delay.o memset.o memcpy.o memmove.o \
> +	   clear_user.o copy_user.o dump_tlb.o
> diff --git a/arch/loongarch/mm/Makefile b/arch/loongarch/mm/Makefile
> new file mode 100644
> index 000000000000..8ffc6383f836
> --- /dev/null
> +++ b/arch/loongarch/mm/Makefile
> @@ -0,0 +1,9 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for the Linux/LoongArch-specific parts of the memory manager.
> +#
> +
> +obj-y				+= init.o cache.o tlb.o tlbex.o extable.o \
> +				   fault.o ioremap.o maccess.o mmap.o pgtable.o page.o
> +
> +obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
> diff --git a/arch/loongarch/pci/Makefile b/arch/loongarch/pci/Makefile
> new file mode 100644
> index 000000000000..8101ef3df71c
> --- /dev/null
> +++ b/arch/loongarch/pci/Makefile
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for the PCI specific kernel interface routines under Linux.
> +#
> +
> +obj-y				+= pci.o
> +obj-$(CONFIG_ACPI)		+= acpi.o
> diff --git a/scripts/subarch.include b/scripts/subarch.include
> index 776849a3c500..4bd327d0ae42 100644
> --- a/scripts/subarch.include
> +++ b/scripts/subarch.include
> @@ -10,4 +10,4 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
>   				  -e s/s390x/s390/ \
>   				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
>   				  -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ \
> -				  -e s/riscv.*/riscv/)
> +				  -e s/riscv.*/riscv/ -e s/loongarch.*/loongarch/)