# SPDX-License-Identifier: GPL-2.0
config ZRAM
	tristate "Compressed RAM block device support"
	depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
	help
	  Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
	  Pages written to these disks are compressed and stored in memory
	  itself. These disks allow very fast I/O and compression provides
	  good amounts of memory savings.

	  It has several use cases, for example: /tmp storage, use as swap
	  disks and maybe many more.

	  See Documentation/admin-guide/blockdev/zram.rst for more information.

config ZRAM_BACKEND_LZ4
	bool "lz4 compression support"
	depends on ZRAM
	select LZ4_COMPRESS
	select LZ4_DECOMPRESS

config ZRAM_BACKEND_LZ4HC
	bool "lz4hc compression support"
	depends on ZRAM
	select LZ4HC_COMPRESS
	select LZ4_DECOMPRESS

config ZRAM_BACKEND_ZSTD
	bool "zstd compression support"
	depends on ZRAM
	select ZSTD_COMPRESS
	select ZSTD_DECOMPRESS

config ZRAM_BACKEND_DEFLATE
	bool "deflate compression support"
	depends on ZRAM
	select ZLIB_DEFLATE
	select ZLIB_INFLATE

config ZRAM_BACKEND_842
	bool "842 compression support"
	depends on ZRAM
	select 842_COMPRESS
	select 842_DECOMPRESS

config ZRAM_BACKEND_FORCE_LZO
	depends on ZRAM
	def_bool !ZRAM_BACKEND_LZ4 && !ZRAM_BACKEND_LZ4HC && \
		!ZRAM_BACKEND_ZSTD && !ZRAM_BACKEND_DEFLATE && \
		!ZRAM_BACKEND_842

config ZRAM_BACKEND_LZO
	bool "lzo and lzo-rle compression support" if !ZRAM_BACKEND_FORCE_LZO
	depends on ZRAM
	default ZRAM_BACKEND_FORCE_LZO
	select LZO_COMPRESS
	select LZO_DECOMPRESS

choice
	prompt "Default zram compressor"
	default ZRAM_DEF_COMP_LZORLE
	depends on ZRAM

config ZRAM_DEF_COMP_LZORLE
	bool "lzo-rle"
	depends on ZRAM_BACKEND_LZO

config ZRAM_DEF_COMP_LZO
	bool "lzo"
	depends on ZRAM_BACKEND_LZO

config ZRAM_DEF_COMP_LZ4
	bool "lz4"
	depends on ZRAM_BACKEND_LZ4

config ZRAM_DEF_COMP_LZ4HC
	bool "lz4hc"
	depends on ZRAM_BACKEND_LZ4HC

config ZRAM_DEF_COMP_ZSTD
	bool "zstd"
	depends on ZRAM_BACKEND_ZSTD

config ZRAM_DEF_COMP_DEFLATE
	bool "deflate"
	depends on ZRAM_BACKEND_DEFLATE

config ZRAM_DEF_COMP_842
	bool "842"
	depends on ZRAM_BACKEND_842

endchoice

config ZRAM_DEF_COMP
	string
	default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
	default "lzo" if ZRAM_DEF_COMP_LZO
	default "lz4" if ZRAM_DEF_COMP_LZ4
	default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
	default "zstd" if ZRAM_DEF_COMP_ZSTD
	default "deflate" if ZRAM_DEF_COMP_DEFLATE
	default "842" if ZRAM_DEF_COMP_842
	default "unset-value"

config ZRAM_WRITEBACK
       bool "Write back incompressible or idle page to backing device"
       depends on ZRAM
       help
	 With incompressible page, there is no memory saving to keep it
	 in memory. Instead, write it out to backing device.
	 For this feature, admin should set up backing device via
	 /sys/block/zramX/backing_dev.

	 With /sys/block/zramX/{idle,writeback}, application could ask
	 idle page's writeback to the backing device to save in memory.

	 See Documentation/admin-guide/blockdev/zram.rst for more information.

config ZRAM_MEMORY_TRACKING
	bool "Track zRam block status"
	depends on ZRAM && DEBUG_FS
	help
	  With this feature, admin can track the state of allocated blocks
	  of zRAM. Admin could see the information via
	  /sys/kernel/debug/zram/zramX/block_state.

	  See Documentation/admin-guide/blockdev/zram.rst for more information.

config ZRAM_MULTI_COMP
	bool "Enable multiple compression streams"
	depends on ZRAM
	help
	  This will enable multi-compression streams, so that ZRAM can
	  re-compress pages using a potentially slower but more effective
	  compression algorithm. Note, that IDLE page recompression
	  requires ZRAM_MEMORY_TRACKING.

config ZRAM_FOR_THP
	bool "Enable THP large folio compression and decompression"
	depends on ZRAM && ZSMALLOC_HIGHORDER_ZSPAGE
	help
	  Enable zram to compress and decompress large folios as a single unit
	  instead of splitting them into PAGE_SIZE. This improves compression
	  ratio and reduces per-page overhead for workloads using transparent
	  huge pages.

	  The folio order is stored in zram metadata at runtime, so all mTHP
	  sizes from order-1 (8K) to order-9 (2MB) are supported without
	  recompilation. Each order has its own huge-class threshold.

config ZRAM_MEMCG
	bool "Enable memory cgroup level zram control"
	depends on ZRAM
	depends on MEMCG
	depends on ZRAM_MULTI_COMP
	select NEED_MEMCG_ZRAM
	help
	  This will enable memcg level ZRAM accounting, compression stream
	  selection and more.

config ZRAM_EMM_COMPRESSION_SETUP
	bool "Enable EMM default multiple compress setup for ZRAM"

	select ZRAM_DEF_COMP_LZ4
	select ZRAM_MULTI_COMP
	select CRYPTO_LZ4
	select CRYPTO_LZO
	select CRYPTO_LZ4HC
	select CRYPTO_ZSTD

	help
	  This sets:
	  priority 1 to use lz4.
	  priority 2 to use lzo-rle.
	  priority 3 to use lz4hc.
	  priority 4 to use zstd.

	  Can be changed at runtime, this config help do a nice default setup,
	  and select required other Kconfigs.
