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5ac8f14ccb
The problem is the following: we have three fixed partitions in a RedBoot partition for kernel, initrd and rootfs. On the surface this looks good. But we have little flash and want to use it efficiently. We want to use the OpenWrt "firmware" partition scheme where the kernel, initramfs and sqashfs+jffs2 rootfs is appended, leaving maximum space for a writeable rootfs. To do this we will override the existing RedBoot partition table with one that merges the three separate partitions into one "firmware" partition. RedBoot is still booting the system. It still needs to read the first two parts "as if" these were the kernel and initrd. This works fine, because the kernel still comes first. We already have hacks in place to merge the two kernel and initrd into one binary image and execute it. This is done by prepending a "prolog" to the kernel that does the necessary copying in memory and then jumps to execute the kernel. Since this "prolog" copying routine is just 92 bytes but has 512 bytes allocated, we can trivially create a firmware format that can be used for splitting the image into kernel and rootfs using a tagging scheme that can be done directly by scripting so we don't need any special binary programs. This splitter implements that idea. This will be used on the Gemini platform and was tested on the Raidsonic IB-4220-B. Link: https://github.com/openwrt/openwrt/pull/21820 Signed-off-by: Linus Walleij <linusw@kernel.org>
122 lines
3 KiB
Text
122 lines
3 KiB
Text
config MTD_SPLIT
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def_bool n
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help
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Generic MTD split support.
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config MTD_SPLIT_SUPPORT
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def_bool MTD = y
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comment "Rootfs partition parsers"
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config MTD_SPLIT_SQUASHFS_ROOT
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bool "Squashfs based root partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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help
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This provides a parsing function which allows to detect the
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offset and size of the unused portion of a rootfs partition
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containing a squashfs.
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comment "Firmware partition parsers"
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config MTD_SPLIT_BCM63XX_FW
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bool "BCM63xx firmware parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_BCM_WFI_FW
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bool "Broadcom Whole Flash Image parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_CFE_BOOTFS
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bool "Parser finding rootfs appended to the CFE bootfs"
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depends on MTD_SPLIT_SUPPORT && (ARCH_BCM4908 || ARCH_BCMBCA)
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select MTD_SPLIT
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help
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cferom on BCM4908 (and bcm63xx) uses JFFS2 bootfs partition
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for storing kernel, cferam and some device specific files.
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There isn't any straight way of storing rootfs so it gets
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appended to the JFFS2 bootfs partition. Kernel needs to find
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it and run init from it. This parser is responsible for
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finding appended rootfs.
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config MTD_SPLIT_SEAMA_FW
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bool "Seama firmware parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_WRGG_FW
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bool "WRGG firmware parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_UIMAGE_FW
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bool "uImage based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_FIT_FW
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bool "FIT based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_LZMA_FW
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bool "LZMA compressed kernel based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_TPLINK_FW
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bool "TP-Link firmware parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_TRX_FW
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bool "TRX image based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_BRNIMAGE_FW
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bool "brnImage (brnboot image) firmware parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_EVA_FW
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bool "EVA image based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_MINOR_FW
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bool "Mikrotik NOR image based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_JIMAGE_FW
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bool "JBOOT Image based firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_ELF_FW
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bool "ELF loader firmware partition parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_H3C_VFS
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bool "Parser finding rootfs appended to H3C VFS"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_SEIL_FW
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bool "IIJ SEIL firmware parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_MSTC_BOOT
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bool "MSTC bootnum-based parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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config MTD_SPLIT_OPENWRT_PROLOG
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bool "OpenWrt executable prolog-based parser"
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depends on MTD_SPLIT_SUPPORT
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select MTD_SPLIT
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