cshoredaniel:

PCS CAP324 (ar9344, ath79)

NAME="OpenWrt"
VERSION="SNAPSHOT"
PRETTY_NAME="OpenWrt SNAPSHOT"
VERSION_ID="snapshot"
BUILD_ID="r10075-ace2410"
LEDE_BOARD="ath79/generic"
LEDE_ARCH="mips_24kc"
LEDE_RELEASE="OpenWrt SNAPSHOT r10075-ace2410"

partitions ending at 0xfa0000 should end at 0xfe0000.
It looks suspiciously like the size of the firmware partition is being used as the end of the rootfs partition.

[ 0.395749] m25p80 spi0.0: mx25l12805d (16384 Kbytes)
[ 0.401067] 4 fixed-partitions partitions found on MTD device spi0.0
[ 0.407631] Creating 4 MTD partitions on "spi0.0":
[ 0.412604] 0x000000000000-0x000000040000 : "u-boot"
[ 0.418554] 0x000000040000-0x000000050000 : "u-boot-env"
[ 0.424883] 0x000000050000-0x000000ff0000 : "firmware"
[ 0.433582] 2 uimage-fw partitions found on MTD device firmware
[ 0.439700] Creating 2 MTD partitions on "firmware":
[ 0.444877] 0x000000000000-0x0000001a0000 : "kernel"
[ 0.450862] 0x0000001a0000-0x000000fa0000 : "rootfs"
[ 0.456702] mtd: device 4 (rootfs) set to be root filesystem
[ 0.462629] 1 squashfs-split partitions found on MTD device rootfs
[ 0.469018] 0x0000004d0000-0x000000fa0000 : "rootfs_data"
[ 0.475393] 0x000000ff0000-0x000001000000 : "art"


https://github.com/openwrt/openwrt/blob/master/target/linux/ath79/dts/ar9344_pcs_cap324.dts

flash@0 {
compatible = "jedec,spi-nor";
reg = <0>;
spi-max-frequency = <25000000>;

	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		uboot: partition@0 {
			label = "u-boot";
			reg = <0x000000 0x040000>;
			read-only;
		};

		partition@40000 {
			label = "u-boot-env";
			reg = <0x040000 0x010000>;
			read-only;
		};

		partition@50000 {
			compatible = "denx,uimage";
			label = "firmware";
			reg = <0x050000 0x0fa0000>;
		};

		art: partition@7f0000 {
			label = "art";
			reg = <0xff0000 0x010000>;
			read-only;
		};
	};

};


Also occurs similarly with CR5000 -- rootfs ends at 0x7a0000 instead of 0x7e0000

https://github.com/openwrt/openwrt/blob/master/target/linux/ath79/dts/ar9344_pcs_cr5000.dts

flash@0 {
compatible = "jedec,spi-nor";
reg = <0>;
spi-max-frequency = <25000000>;

	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		uboot: partition@0 {
			label = "u-boot";
			reg = <0x000000 0x040000>;
			read-only;
		};

		partition@40000 {
			label = "u-boot-env";
			reg = <0x040000 0x010000>;
			read-only;
		};

		partition@50000 {
			compatible = "denx,uimage";
			label = "firmware";
			reg = <0x050000 0x07a0000>;
		};

		art: partition@7f0000 {
			label = "art";
			reg = <0x7f0000 0x010000>;
			read-only;
		};

};


/proc/cmdline is console=ttyS0,115200 rootfstype=squashfs,jffs2 so it's not reading from e.g. mtdparts