I can not reproduce this issue on my side. EXT4 USB disk works fine. Hardware: Babbage Board 2.5 Image: Alpha2 release + apt-get dist-upgrade Kernel: -- $ uname -a Linux babbage 2.6.31-602-imx51 #4-Ubuntu Mon Jan 11 17:05:57 UTC 2010 armv7l GNU/Linux -- I created a 1G EXT4 USB disk on my Karmic desktop and mounted it on my Babbage board. Wrote 10M file to the USB disk and can read out it on my desktop machine. -- roc@babbage:/media$ cd 1G_EXT4/ roc@babbage:/media/1G_EXT4$ ls lost+found roc@babbage:/media/1G_EXT4$ dd if=/dev/zero of=data.bin bs=1M count=10 10+0 records in 10+0 records out 10485760 bytes (10 MB) copied, 0.140188 s, 74.8 MB/s roc@babbage:/media/1G_EXT4$ cd .. roc@babbage:/media$ umount 1G_EXT4/ roc@babbage:/media$ ls 4B4D-D0D4 cdrom cdrom0 roc@babbage:/media$ dmesg Initializing cgroup subsys cpuset Initializing cgroup subsys cpu Linux version 2.6.31-602-imx51 (buildd@huito) (gcc version 4.4.3 20100108 (prerelease) (Ubuntu 4.4.2-9ubuntu3) ) #4-Ubuntu Mon Jan 11 17:05:57 UTC 2010 (Ubuntu 2.6.31-602.4-imx51) CPU: ARMv7 Processor [412fc081] revision 1 (ARMv7), cr=10c53c7f CPU: VIPT nonaliasing data cache, VIPT nonaliasing instruction cache Machine: Freescale MX51 Babbage Board Memory policy: ECC disabled, Data cache writeback On node 0 totalpages: 122880 free_area_init_node: node 0, pgdat c060cc24, node_mem_map c0682000 DMA zone: 128 pages used for memmap DMA zone: 0 pages reserved DMA zone: 16256 pages, LIFO batch:3 Normal zone: 832 pages used for memmap Normal zone: 105664 pages, LIFO batch:31 Built 1 zonelists in Zone order, mobility grouping on. Total pages: 121920 Kernel command line: root=UUID=fd8c99d5-8e53-4d99-9d4e-75b8c96e7b94 ro quiet splash PID hash table entries: 2048 (order: 11, 8192 bytes) Dentry cache hash table entries: 65536 (order: 6, 262144 bytes) Inode-cache hash table entries: 32768 (order: 5, 131072 bytes) allocated 2457600 bytes of page_cgroup please try 'cgroup_disable=memory' option if you don't want memory cgroups Memory: 480MB = 480MB total Memory: 468552KB available (5744K code, 692K data, 176K init, 0K highmem) SLUB: Genslabs=11, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 NR_IRQS:272 MXC IRQ initialized Console: colour dummy device 80x30 console [tty0] enabled Calibrating delay loop... 799.53 BogoMIPS (lpj=3997696) Security Framework initialized AppArmor: AppArmor initialized Mount-cache hash table entries: 512 Initializing cgroup subsys ns Initializing cgroup subsys cpuacct Initializing cgroup subsys memory Initializing cgroup subsys freezer Initializing cgroup subsys net_cls CPU: Testing write buffer coherency: ok regulator: core version 0.5 NET: Registered protocol family 16 CPU is i.MX51 Revision 2.0 MXC GPIO hardware iomux_config_mux: Warning: iomux pin config changed, reg=fb0a8134, prev=0x1 new=0x3 IRAM READY mxc_init_dvfs_per initialised Using SDMA I.API MXC DMA API initialized bio: create slab at 0 SCSI subsystem initialized libata version 3.00 loaded. CSPI: mxc_spi-0 probed usbcore: registered new interface driver usbfs usbcore: registered new interface driver hub usbcore: registered new device driver usb MXC I2C driver MXC I2C driver MXC HS I2C driver PMIC Light driver loading... Bluetooth: Core ver 2.15 NET: Registered protocol family 31 Bluetooth: HCI device and connection manager initialized Bluetooth: HCI socket layer initialized NET: Registered protocol family 8 NET: Registered protocol family 20 NetLabel: Initializing NetLabel: domain hash size = 128 NetLabel: protocols = UNLABELED CIPSOv4 NetLabel: unlabeled traffic allowed by default mc13892 Rev 2.0 FinVer 0 detected Initializing regulators for Babbage. regulator: SW1: 600 <--> 1375 mV regulator: SW2: 900 <--> 1850 mV regulator: SW3: 1100 <--> 1850 mV regulator: SW4: 1100 <--> 1850 mV regulator: SWBST: 0 mV regulator: VIOHI: 0 mV regulator: VPLL: 1050 <--> 1800 mV regulator: VDIG: 1650 mV regulator: VSD: 1800 <--> 3150 mV regulator: VUSB2: 2400 <--> 2775 mV regulator: VVIDEO: 2775 mV regulator: VAUDIO: 2300 <--> 3000 mV regulator: VCAM: 2500 <--> 3000 mV fast normal regulator: VGEN1: 1200 mV regulator: VGEN2: 1200 <--> 3150 mV regulator: VGEN3: 1800 <--> 2900 mV regulator: VUSB: 0 mV regulator: GPO1: 0 mV regulator: GPO2: 0 mV regulator: GPO3: 0 mV regulator: GPO4: 0 mV PMIC ADC start probe PMIC Light successfully loaded Device spi1.0 probed AppArmor: AppArmor Filesystem Enabled NET: Registered protocol family 2 IP route cache hash table entries: 4096 (order: 2, 16384 bytes) TCP established hash table entries: 16384 (order: 5, 131072 bytes) TCP bind hash table entries: 16384 (order: 4, 65536 bytes) TCP: Hash tables configured (established 16384 bind 16384) TCP reno registered NET: Registered protocol family 1 Trying to unpack rootfs image as initramfs... Switched to high resolution mode on CPU 0 Freeing initrd memory: 9472K LPMode driver module loaded Static Power Management for Freescale i.MX51 PM driver module loaded sdram autogating driver module loaded Bus freq driver module loaded DVI monitor is primary usb: Host 1 host (isp1504) registered usb: DR host (utmi) registered usb: DR gadget (utmi) registered mxc_dvfs_core_probe DVFS driver module loaded i.MXC CPU frequency driver DVFS PER driver module loaded audit: initializing netlink socket (disabled) type=2000 audit(1.170:1): initialized VFS: Disk quotas dquot_6.5.2 Dquot-cache hash table entries: 1024 (order 0, 4096 bytes) fuse init (API version 7.12) msgmni has been set to 934 alg: No test for stdrng (krng) io scheduler noop registered io scheduler anticipatory registered io scheduler deadline registered io scheduler cfq registered (default) fbcvt: 1024x768@60: CVT Name - .786M3 mxc_ipu mxc_ipu: Channel already disabled 9 mxc_ipu mxc_ipu: Channel already uninitialized 9 Console: switching to colour frame buffer device 128x48 fbcvt: 1024x768@60: CVT Name - .786M3 regulator: get() with no identifier regulator: get() with no identifier regulator: get() with no identifier mxci2c_wait_writefifo:wait error Serial: MXC Internal UART driver mxcintuart.0: ttymxc0 at MMIO 0x73fbc000 (irq = 31) is a Freescale i.MX mxcintuart.1: ttymxc1 at MMIO 0x73fc0000 (irq = 32) is a Freescale i.MX mxcintuart.2: ttymxc2 at MMIO 0x7000c000 (irq = 33) is a Freescale i.MX brd: module loaded loop: module loaded Fixed MDIO Bus: probed FEC Ethernet Driver fec: PHY @ 0x0, ID 0x0007c0c4 -- LAN8700 PPP generic driver version 2.4.2 MXC MTD nor Driver 2.0 MXC MTD nand Driver 2.5 ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver fsl-ehci fsl-ehci.0: Freescale On-Chip EHCI Host Controller fsl-ehci fsl-ehci.0: new USB bus registered, assigned bus number 1 fsl-ehci fsl-ehci.0: irq 14, io base 0x73f80200 fsl-ehci fsl-ehci.0: USB 2.0 started, EHCI 1.00 usb usb1: configuration #1 chosen from 1 choice hub 1-0:1.0: USB hub found hub 1-0:1.0: 1 port detected fsl-ehci fsl-ehci.1: Freescale On-Chip EHCI Host Controller fsl-ehci fsl-ehci.1: new USB bus registered, assigned bus number 2 fsl-ehci fsl-ehci.1: irq 18, io base 0x73f80000 fsl-ehci fsl-ehci.1: USB 2.0 started, EHCI 1.00 usb usb2: configuration #1 chosen from 1 choice hub 2-0:1.0: USB hub found hub 2-0:1.0: 1 port detected Initializing USB Mass Storage driver... usbcore: registered new interface driver usb-storage USB Mass Storage support registered. ARC USBOTG Device Controller driver (1 August 2005) udc: request mem region for fsl-usb2-udc failed fsl-usb2-udc: probe of fsl-usb2-udc failed with error -16 mice: PS/2 mouse device common for all mice MXC keypad loaded clk: Unable to get requested clock: kpp_clk input: mxckpd as /devices/virtual/input/input0 mc13892 rtc probe start pmic_rtc pmic_rtc.1: rtc core: registered pmic_rtc as rtc0 mc13892 rtc probe succeed i2c /dev entries driver APM Battery Driver MXC WatchDog Driver 2.0 clk: Unable to get requested clock: wdog_clk MXC Watchdog # 0 Timer: initial timeout 60 sec device-mapper: uevent: version 1.0.3 device-mapper: ioctl: 4.15.0-ioctl (2009-04-01) initialised: