On Friday 16 November 2012 00:18:22 Michel Benoit wrote:
> Hi,
>
> I'm trying to mount a YAFFS partition in u-boot so that I can read/write
> files that are in an existing YAFFS partition created with linux.
> I've built u-boot v2012.10 with som very minor changes to support our
> embedded linux board (similar to at91sam9260ek).
>
> From linux I have the following partitions
>
> # cat /proc/mtd
> dev:    size   erasesize  name
> mtd0: 00040000 00020000 "uboot-env0"
> mtd1: 00040000 00020000 "uboot-env1"
> mtd2: 00400000 00020000 "kernel0"
> mtd3: 00400000 00020000 "kernel1"
> mtd4: 01400000 00020000 "rootfs0"
> mtd5: 01400000 00020000 "rootfs1"
> mtd6: 1cf00000 00020000 "user"
> mtd7: 00020000 00020000 "bootstrap"
> mtd8: 00060000 00020000 "uboot"
>
> # cat /proc/mounts
> rootfs / rootfs rw 0 0
> /dev/root / yaffs2 rw,relatime 0 0
> devtmpfs /dev devtmpfs rw,relatime,size=14148k,nr_inodes=3537,mode=755 0 0
> proc /proc proc rw,relatime 0 0
> devpts /dev/pts devpts rw,relatime,gid=5,mode=620 0 0
> tmpfs /dev/shm tmpfs rw,relatime,mode=777 0 0
> tmpfs /tmp tmpfs rw,relatime 0 0
> sysfs /sys sysfs rw,relatime 0 0
> none /proc/bus/usb usbfs rw,relatime 0 0
> /dev/mtdblock6 /mnt/flash yaffs2 rw,relatime 0 0
>
> Where the MTD partitions are defined in the linux borad file as:
>
> static struct mtd_partition __initdata exyp_nand_partition[] = {
>         {
>                 .name   = "uboot-env0",
>                 .offset = 0x00080000,
>                 .size   = 0x00040000,  /* two erase blocks (256kB) */
>         },
>         {
>                 .name   = "uboot-env1",
>                 .offset = 0x000C0000,
>                 .size   = 0x00040000,  /* two erase blocks (256kB) */
>         },
>         {
>                 .name   = "kernel0",
>                 .offset = 0x00100000,
>                 .size   = 0x00400000,  /* 4MB */
>         },
>         {
>                 .name   = "kernel1",
>                 .offset = 0x00500000,
>                 .size   = 0x00400000,  /* 4MB */
>         },
>         {
>                 .name   = "rootfs0",
>                 .offset = 0x00900000,
>                 .size   = 0x01400000,  /* 20MB */
>         },
>         {
>                 .name   = "rootfs1",
>                 .offset = 0x01D00000,
>                 .size   = 0x01400000,  /* 20MB */
>         },
>         {
>                 .name   = "user",
>                 .offset = 0x03100000,
>                 .size   = 0x1cf00000,  /* 463MB */
>         },
>         {
>                 .name   = "bootstrap",
>                 .offset = 0,
>                 .size   = 0x00020000,  /* one erase block (128kB) */
>         },
>         {
>                 .name   = "uboot",
>                 .offset = 0x00020000,
>                 .size   = 0x00060000, /* three erase blocks (384kB) */
>         },
>
> };
>
>
> Both rootfs and user MTD partitions are formatted YAFFS with file content.
>
> When I try to access the yaffs file systems from u-boot I can mount them
> but they are empty.
> I can store files to the and make directories etc but I get no access to
> the existing files in the partitions created within linux and the files
> disappear after a reboot.
>
> U-Boot> version
>
> U-Boot 2012.10 (Nov 15 2012 - 11:10:15)
> arm-linux-gcc (Buildroot 2011.11-svn407) 4.3.6
> GNU ld (GNU Binutils) 2.21.1
>
> U-Boot> nand info
>
> Device 0: nand0, sector size 128 KiB
>   Page size      2048 b
>   OOB size         64 b
>   Erase size   131072 b
>
> U-Boot> ydevconfig user 0 0x188 0xfff
> Configures yaffs mount user: dev 0 start block 392, end block 4095
>
> U-Boot> ydevconfig rootfs 0 0xe8 0x187
> Configures yaffs mount rootfs: dev 0 start block 232, end block 391
>
> U-Boot> ydevls
> rootfs         0 0x000e8 0x00187 not mounted
> user           0 0x00188 0x00fff not mounted
>
> U-Boot> ymount user
> Mounting yaffs2 mount point user
> U-Boot> ymount rootfs
> Mounting yaffs2 mount point rootfs
> U-Boot> yls rootfs
> lost+found
> U-Boot> yls user
> lost+found
>
> U-Boot> ywr user/foo 0x55 10
> Writing value (55) 10 times to user/foo... done
>
> U-Boot> yls user
> foo
> lost+found
>
> <REBOOT>
>
> U-Boot> ydevconfig user 0 0x188 0xfff
> Configures yaffs mount user: dev 0 start block 392, end block 4095
> U-Boot> ymount user
> Mounting yaffs2 mount point user
> U-Boot> yls user
> lost+found
>
>
> It seems that YAFFS is mounting on top of RAM instead of on the NAND chip.
> Do I have to specify mtd parts in u-boot order to access the NAND?
> Is there a u-boot config define for selecting NAND or RAM for YAFFS2
> support?

Why do you think it is writing to RAM?

A few things to try:
1. Try turning on tracing and seeing if you get any further info.
2. What happens if you save a file under u-boot then reboot back into u-boot. 
Is the file still there?

These problems are almost always due to incompatibilities between the mtd in 
u-boot and Linux.


>
> My ultimate goal is to read out the linux kernel image from the rootfs
> (YAFFS), copy it to RAM and boot.

That is a most achievable goal.

-- Charles