From a60721f2ed3b0152821d2a82e5e7ed115a8ae9cc Mon Sep 17 00:00:00 2001 From: =?utf8?q?Micha=C5=82=20K=C4=99pie=C5=84?= Date: Mon, 13 May 2024 19:26:15 +0200 Subject: [PATCH] mikrotik: switch to Yafut for building MikroTik NOR images MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The Yafut tool now has limited capabilities for working on filesystem images stored in regular files. This enables preparing Yaffs2 images for devices with NOR flash using upstream Yaffs2 filesystem code instead of the custom kernel2minor tool. Since minimizing the size of the resulting filesystem image size is important and upstream Yaffs2 code requires two allocator reserve blocks to be available when writing a file to the filesystem, a trick is employed while preparing an OpenWRT image: the blank filesystem image that Yafut operates on initially contains two extra erase blocks that are chopped off after the kernel file is written. This is safe to do because Yaffs2 has a true log structure and therefore only ever writes sequentially (and the size of the kernel file is known beforehand). While the two extra erase blocks are necessary for writes, Yaffs2 code seems to be perfectly capable of reading back files from a "truncated" filesystem that does not contain these extra erase blocks. In terms of image size, this new approach is only marginally worse than the current kernel2minor-based one: specifically, upstream Yaffs2 code needs to write three object headers (each of which takes up an entire data chunk) when the kernel file is written to the filesystem: - an object header for the kernel file when it is created, - an object header for the root directory when the kernel file is created, - an updated object header for the kernel file when the latter is fully written (so that its new size can be recorded). kernel2minor only writes two of these headers, which is the absolute minimum required for reading the file back. This means that the Yafut-based approach causes firmware images to be at most one erase block (64 kB) larger than those created using kernel2minor, but only in the very unfortunate scenario where the size of the kernel file is really close to a multiple of the erase block size. The rest of the calculations performed when the empty filesystem image is first prepared stems from the Yaffs2 layout used by MikroTik NOR devices: each 65,536-byte erase block contains 63 chunks, each of which consists of 1024 bytes of data followed by 16-byte Yaffs tags without ECC data; each such group of 63 chunks is then followed by 16 bytes of padding, which translates to "-C 1040 -B 64k -E" in the Yafut invocation. Yaffs2 checkpoints and summaries are disabled (using Yafut's -P and -S switches, respectively) as they are merely performance optimizations that require extra storage space. The -L and -M switches are used to force little-endian or big-endian byte order (respectively) in the resulting filesystem image, no matter what byte order the build host uses. The tr invocation is used to ensure that the filesystem image is initialized with 0xFF bytes (which are an indicator of unused space for Yaffs2 code). Signed-off-by: Michał Kępień Link: https://github.com/openwrt/openwrt/pull/13453 Signed-off-by: Robert Marko --- include/image-commands.mk | 14 ++++++++++++++ target/linux/ath79/image/common-mikrotik.mk | 2 +- target/linux/ipq40xx/image/mikrotik.mk | 2 +- target/linux/ramips/image/mt7621.mk | 2 +- tools/Makefile | 2 ++ 5 files changed, 19 insertions(+), 3 deletions(-) diff --git a/include/image-commands.mk b/include/image-commands.mk index 83ecf7c520..f2c3f76f91 100644 --- a/include/image-commands.mk +++ b/include/image-commands.mk @@ -438,6 +438,20 @@ define Build/kernel2minor rm -f $(temp_file) endef +define Build/yaffs-filesystem + let \ + kernel_size="$$(stat -c%s $@)" \ + kernel_chunks="(kernel_size / 1024) + 1" \ + filesystem_chunks="kernel_chunks + 3" \ + filesystem_blocks="(filesystem_chunks / 63) + 1" \ + filesystem_size="filesystem_blocks * 64 * 1024" \ + filesystem_size_with_reserve="(filesystem_blocks + 2) * 64 * 1024"; \ + head -c $$filesystem_size_with_reserve /dev/zero | tr "\000" "\377" > $@.img \ + && yafut -d $@.img -w -i $@ -o kernel -C 1040 -B 64k -E -P -S $(1) \ + && truncate -s $$filesystem_size $@.img \ + && mv $@.img $@ +endef + define Build/kernel-bin rm -f $@ cp $< $@ diff --git a/target/linux/ath79/image/common-mikrotik.mk b/target/linux/ath79/image/common-mikrotik.mk index b37c8b7197..94c29d8cb6 100644 --- a/target/linux/ath79/image/common-mikrotik.mk +++ b/target/linux/ath79/image/common-mikrotik.mk @@ -10,7 +10,7 @@ endef define Device/mikrotik_nor $(Device/mikrotik) DEVICE_PACKAGES := -yafut - IMAGE/sysupgrade.bin := append-kernel | kernel2minor -s 1024 -e | \ + IMAGE/sysupgrade.bin := append-kernel | yaffs-filesystem -M | \ pad-to $$$$(BLOCKSIZE) | append-rootfs | pad-rootfs | \ check-size | append-metadata endef diff --git a/target/linux/ipq40xx/image/mikrotik.mk b/target/linux/ipq40xx/image/mikrotik.mk index f0e1f1aad3..8c2c6fa08e 100644 --- a/target/linux/ipq40xx/image/mikrotik.mk +++ b/target/linux/ipq40xx/image/mikrotik.mk @@ -5,7 +5,7 @@ define Device/mikrotik_nor KERNEL_NAME := vmlinux KERNEL := kernel-bin | append-dtb-elf IMAGES = sysupgrade.bin - IMAGE/sysupgrade.bin := append-kernel | kernel2minor -s 1024 | \ + IMAGE/sysupgrade.bin := append-kernel | yaffs-filesystem -L | \ pad-to $$$$(BLOCKSIZE) | append-rootfs | pad-rootfs | \ check-size | append-metadata endef diff --git a/target/linux/ramips/image/mt7621.mk b/target/linux/ramips/image/mt7621.mk index 8886456bbb..0643cd29f4 100644 --- a/target/linux/ramips/image/mt7621.mk +++ b/target/linux/ramips/image/mt7621.mk @@ -1770,7 +1770,7 @@ define Device/MikroTik DEVICE_PACKAGES := kmod-usb3 -uboot-envtools KERNEL_NAME := vmlinuz KERNEL := kernel-bin | append-dtb-elf - IMAGE/sysupgrade.bin := append-kernel | kernel2minor -s 1024 | \ + IMAGE/sysupgrade.bin := append-kernel | yaffs-filesystem -L | \ pad-to $$$$(BLOCKSIZE) | append-rootfs | pad-rootfs | check-size | \ append-metadata endef diff --git a/tools/Makefile b/tools/Makefile index f60a458f98..f4e749d710 100644 --- a/tools/Makefile +++ b/tools/Makefile @@ -83,6 +83,7 @@ tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_TARGET_mxs),y) += elftosb sdim tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_TARGET_realtek),y) += 7z tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_TARGET_tegra),y) += cbootimage cbootimage-configs tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_USES_MINOR),y) += kernel2minor +tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_USES_MINOR),y) += yafut tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_USE_SPARSE),y) += sparse tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_USE_LLVM_BUILD),y) += llvm-bpf tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(CONFIG_USE_MOLD),y) += mold @@ -130,6 +131,7 @@ $(curdir)/sdcc/compile := $(curdir)/bison/compile $(curdir)/squashfs3-lzma/compile := $(curdir)/lzma-old/compile $(curdir)/squashfs4/compile := $(curdir)/xz/compile $(curdir)/zlib/compile $(curdir)/util-linux/compile := $(curdir)/bison/compile +$(curdir)/yafut/compile := $(curdir)/cmake/compile ifneq ($(HOST_OS),Linux) $(curdir)/coreutils/compile += $(curdir)/automake/compile $(curdir)/bison/compile $(curdir)/gnulib/compile -- 2.30.2