rt3200 mumble
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Daniel Barlow
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1 changed files with 255 additions and 0 deletions
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THOUGHTS.txt
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THOUGHTS.txt
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@ -2436,3 +2436,258 @@ Sun Sep 17 16:44:31 BST 2023
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Can we figure out which bits of the old doc are missing from the new
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one and just transplant those? Then we can merge it sooner
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instead of blocking on writig all the new stuff
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Mon Sep 25 16:58:51 BST 2023
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jffs2 on mt300a isn't finding root partition in initramfs, and it
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seems to be because MTD_SPLIT_UIMAGE_FW isn't working
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[ 0.426792] spi spi0.0: force spi mode3
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[ 0.431305] spi-nor spi0.0: w25q128 (16384 Kbytes)
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[ 0.436322] 5 fixed-partitions partitions found on MTD device spi0.0
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[ 0.442875] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
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[ 0.450400] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
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[ 0.458208] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
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[ 0.465751] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
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[ 0.473522] Creating 5 MTD partitions on "spi0.0":
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[ 0.478466] 0x000000000000-0x000000030000 : "u-boot"
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[ 0.484447] 0x000000030000-0x000000040000 : "u-boot-env"
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[ 0.490888] 0x000000040000-0x000000050000 : "factory"
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[ 0.497110] 0x000000050000-0x000000fd0000 : "firmware"
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[ 0.596423] 0x000000ff0000-0x000001000000 : "art"
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[ 0.611508] gsw: setting port4 to ephy mode
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with squashfs root it's the same but for the extra split partitions:
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[ 0.468715] Creating 5 MTD partitions on "spi0.0":
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[ 0.473653] 0x000000000000-0x000000030000 : "u-boot"
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[ 0.479652] 0x000000030000-0x000000040000 : "u-boot-env"
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[ 0.486085] 0x000000040000-0x000000050000 : "factory"
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[ 0.492318] 0x000000050000-0x000000fd0000 : "firmware"
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[ 0.499304] 2 uimage-fw partitions found on MTD device firmware
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[ 0.505457] Creating 2 MTD partitions on "firmware":
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[ 0.510543] 0x000000000000-0x000000260000 : "kernel"
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[ 0.516616] 0x000000260000-0x000000f80000 : "rootfs"
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[ 0.522570] mtd: device 5 (rootfs) set to be root filesystem
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[ 0.528565] 0x000000ff0000-0x000001000000 : "art"
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turns out this is because the device thinks it has 4k erase block size
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because MTD_SPI_NOR_USE_4K_SECTORS was set, and that was causing
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mtdsplit to look in the wrong place for a root filesystem
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Mon Sep 25 18:50:05 BST 2023
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No, that wasn't it. Turned out to be an endianness-dependent check for
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JFFS2 magic in mtdsplit.
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setenv serverip 10.0.0.1
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setenv ipaddr 10.0.0.8
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tftp 0xa00000 result/uimage
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bootm 0xa00000
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Fri Sep 29 20:50:39 BST 2023
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setenv bootargs 'liminix mtdparts=phram0:M(rootfs) phram.phram=phram0,0x40411f28,4194304,65536 memmap=4194304$0x40411f28 root=/dev/mtdblock0 console=ttyAMA0,115200 earlycon'
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setenv serverip 10.0.0.1
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setenv ipaddr 10.0.0.5
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setenv bootargs 'liminix console=ttyS0,115200 panic=10 oops=panic earlycon=uart8250,mmio32,0x11002000 root=/dev/mtdblock0'
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tftp 0x4007ff28 result/uimage ; tftp 0x40432f28 result/rootfs
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bootm 0x4007ff28
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setenv bootargs 'liminix console=ttyS0,115200 panic=1 oops=panic earlycon root=/dev/mtdblock0'
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md 0x42ff0000
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Cannot find regmap for /infracfg@10000000: -524.
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# "console=ttyAMA0,38400 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/mtdblock0 rootfstype=squashfs fw_devlink=off"
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40812468: 69726553 203a6c61 41424d41 304c5020 Serial: AMBA PL0
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40812478: 55203131 20545241 76697264 3c0a7265 11 UART driver.<
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40812488: 61723e33 706f6f6d 61203a73 6165726c 3>ramoops: alrea
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40812498: 69207964 6974696e 7a696c61 3c0a6465 dy initialized.<
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408124a8: 61723e34 706f6f6d 70203a73 65626f72 4>ramoops: probe
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408124b8: 20666f20 66663234 30303030 6d61722e of 42ff0000.ram
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408124c8: 73706f6f 69616620 2064656c 68746977 oops failed with
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408124d8: 72726520 2d20726f 3c0a3232 61433e33 error -22.<3>Ca
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408124e8: 746f6e6e 6e696620 65722064 70616d67 nnot find regmap
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408124f8: 726f6620 6e692f20 63617266 31406766 for /infracfg@1
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40812508: 30303030 3a303030 32352d20 333c0a34 0000000: -524.<3
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40812518: 6e61433e 20746f6e 646e6966 67657220 >Cannot find reg
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MT7622>
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40812528: 2070616d 20726f66 666e692f 66636172 map for /infracf
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40812538: 30314067 30303030 203a3030 3432352d g@10000000: -524
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40812548: 3e333c0a 6e6e6143 6620746f 20646e69 .<3>Cannot find
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40812558: 6d676572 66207061 2f20726f 72666e69 regmap for /infr
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40812568: 67666361 30303140 30303030 2d203a30 acfg@10000000: -
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40812578: 0a343235 433e333c 6f6e6e61 69662074 524.<3>Cannot fi
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40812588: 7220646e 616d6765 6f662070 702f2072 nd regmap for /p
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40812598: 63697265 31406766 32303030 3a303030 ericfg@10002000:
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408125a8: 32352d20 313c0a34 616e553e 20656c62 -524.<1>Unable
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408125b8: 68206f74 6c646e61 656b2065 6c656e72 to handle kernel
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408125c8: 67617020 20676e69 75716572 20747365 paging request
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408125d8: 76207461 75747269 61206c61 65726464 at virtual addre
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408125e8: 66207373 66666666 66666666 66666666 ss fffffffffffff
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408125f8: 0a656666 4d3e313c 61206d65 74726f62 ffe.<1>Mem abort
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CONFIG_SERIAL_8250_FSL=y
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CONFIG_SERIAL_8250_MT6577=y
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CONFIG_SERIAL_8250_NR_UARTS=3
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CONFIG_SERIAL_8250_RUNTIME_UARTS=3
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CONFIG_SERIAL_DEV_BUS=y
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CONFIG_SERIAL_DEV_CTRL_TTYPORT=y
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CONFIG_SERIAL_MCTRL_GPIO=y
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CONFIG_SERIAL_OF_PLATFORM=y
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Mon Oct 2 10:17:04 BST 2023
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We have a bootable aarch64 kernel for the Belkin, but it does not
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understand the memmap= parameter we're using to protect the
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phram image from being used as general memory.
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One option is to add a reserved-memory stanza in the device tree,
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using u-boot "fdt" command, but we don't know the fdt address in u-boot
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because it doesn't have any commands to parse the image and set
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variables pointing at the sub-components. (There's iminfo, but it's
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onyl human-readable)
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Second option is to amend the dtb in the tftpboot module: this
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would mean regenerating the uimage
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Third option: for tftpboot do we _have_ to use FIT? maybe we could
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grab the fdt as a separate tftp transaction
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we need to apply kernel patch 9401911f2d9f89035f7acebab16e72d43d1282fb
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to avoid using ioremap on sysem ram which is not allowed on arm
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Tue Oct 3 14:15:38 BST 2023
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Progress on Liminix ARM support. The device I'm starting with is
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the Belkin RT3200 (also known as [Linksys E8450](https://openwrt.org/toh/linksys/e8450)) which seems to be a featureful piece of kit, and whioch I snagged for a
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very good price on the Bay of E
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# Where are we right now?
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* we can TFTP boot it to userland
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* ethernet works
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## What else needs doing?
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* it has dual band wifi with many interesting features. I've built the
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* we're only running in RAM, probably need to add some kernel config
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to support the flash
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* initramfs support is not yet implemented
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* the flash is NAND flash and it's quite large compared with the
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existing Liminix devices, so we're going to add UBIFS which will
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use it better than JFFS2 does
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* all this work is on a branch and needs to be cleaned up a lot before
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I'm letting it into main
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## What have we found?
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There are some significant differences between this and the MIPS
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devices (yes, other than an entirely different architecture), mostly
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to do with "legacy boot" support or the lack thereof. For example:
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* there aren't any options like `MIPS_RAW_APPENDED_DTB` to glom
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together a kernel and device tree (FDT), because the bootloader is
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expected to be able to provide a FDT following "standards".
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U-Boot will do this, provided that we use the newer "FIT" Uimage
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format which allows a kernel and DTB and initrd to be combined in
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the same container. (Sadly we can't use FIT everywhere because a
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lot of MIPS devices use really old forks of U-Boot that don't
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understand it)
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* for tftpboot, on MIPS we use the `memmap` kernel command line option
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to reserve some RAM for the root filesystem. On Arm there's no such
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option, so we have to add a
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[reserved-memory](https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml)
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node in the device tree instead. Which means, given that we _only_
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want to do this when tftp booting (the memory is wasted
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otherwise), we have to rewrite the device tree in that
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scenario.
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* then it turns out that phram doesn't (didn't) work anyway, because
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it calls ioremap() and [you can't use ioremap on system memory on ARM](https://lwn.net/Articles/409689/). In newer kernels this is
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fixed: there is a [conditional](https://github.com/torvalds/linux/blob/master/drivers/mtd/devices/phram.c#L127) here to use whichever of ioremap or
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memremap is appropriate for the memory passed to phram, but it looks
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non-trivial to backport so I've gone for a [much less sophisticated approach](https://gti.telent.net/dan/liminix/commit/f7cd9c2b6e6c99a228e066b09e3febcf71c63fa1#diff-d8e355f1b2dcde7378ebb40c92cdd2ce3125753c)
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* we're using [DSA](https://www.kernel.org/doc/Documentation/networking/dsa/dsa.txt) instead of the OpenWrt [swconfig](https://openwrt.org/docs/techref/swconfig) program. There was actually surprisingly little work needed to adjust to this.
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Other than that, it was mostly the usual process of "did the kernel
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crash silently, or has it just been unable to open a console device?".
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In this regard, *one neat trick*: even though U-Boot on this device
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doesn't support pstore, we can use it anyway if we don't do compression.
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Enable
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```
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PSTORE = "y";
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PSTORE_RAM = "y";
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PSTORE_CONSOLE = "y";
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PSTORE_DEFLATE_COMPRESS = "n";
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```
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then boot with `panic=3 oops=panic`, then when it resets use the
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U_Boot `md` command to see what happened:
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```
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MT7622> md 0x42ff0000
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42ff0000: 43474244 00000000 00000ff4 3d3d3d3d DBGC........====
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42ff0010: 39342e31 36373031 500a442d 63696e61 1.491076-D.Panic
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42ff0020: 50203123 31747261 3e363c0a 20505050 #1 Part1.<6>PPP
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42ff0030: 20445342 706d6f43 73736572 206e6f69 BSD Compression
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[....]
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42ff0ca0: 20676e69 73756e75 6b206465 656e7265 ing unused kerne
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42ff0cb0: 656d206c 79726f6d 3731203a 0a4b3832 l memory: 1728K.
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42ff0cc0: 523e363c 2f206e75 74696e69 20736120 <6>Run /init as
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42ff0cd0: 74696e69 6f727020 73736563 3e373c0a init process.<7>
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```
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Wed Oct 4 21:08:44 BST 2023
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By randomly including chinks of the openwrt config we have made it
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find the mt7915e on the pcie bus. I just don't yet know which bit of
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the openwrt config it was.
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It doesn't actually work yet though. 5GHz wifi gets calibration data
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from the flash, so it is not going to work unless (1) we reflash the
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firmware partition, or (2) we find another way to provide it
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calibration data.
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https://forum.openwrt.org/t/belkin-rt3200-linksys-e8450-wifi-ax-discussion/94302/401
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Sat Oct 7 22:56:40 BST 2023
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We're almost ready to merge the rt3200 support (it's not finished
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but it mostly won't break mips) except for the uimage module
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which needs all that FIT stuff, and the tftpboot contortions
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to amend the dtb for memmap
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For legacy uimage
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1) add commandline params to dtb
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2) objcopy fdt into vmlinux.elf
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3) strip to raw image and compress
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4) mkimage
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For FIT uimage
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1) add commandline params to dtb
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2) strip to raw image and compress
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3) create its file
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4) mkimage
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Do we still want to handle the no-dtb case? what about
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standards-compliant boot, where u-boot is providing the dtb? No option
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to provide a commandline in that case, but maybe also no need to.
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For tftpboot, am undecided. We could use the dtb rewriting thing
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everywhere, in the interest of consistency.
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