Create FAT partition/filesystem on the internal microSD flash of the Dreamplug

[Mattia Rossi]

Hi Ian,

I finally came around to test the attached patch for newfs_msdosfs on 
the dreamplug, and I can confirm that it works!

It also still works on i386/x86_64 and the disk formatted on ARM is 
recognised properly on all systems.

Is it still possible to commit this patch to 9?

I believe it's a very useful and non problematic commit.

Mat

On 17/10/2011 03:50, Ian Lepore wrote:
> On Thu, 2011-10-13 at 15:32 +1100, Mattia Rossi wrote:
>> On 13/10/11 02:06, Warner Losh wrote:
>>>
>>> On Oct 12, 2011, at 12:38 AM, Mattia Rossi wrote:
>>>
>>>> -snip-
>>>>>>> I've tried to recreate it using gpart and newfs_msdos, but can't
>>>>>>> create any new FAT partition that mount_msdosfs would mount.
>>>>>>> [snip]
>
> This turned out to be a difference in structure packing (it's something
> that happens a lot with ARM).  The patch below should get it working for
> you.
>
> Funny aside:  I opened newfs_msdos.c and within 90 seconds knew what was
> wrong and how to fix it.  It then took me over an hour to prove to
> myself that my fix was right -- the mount was failing because I forgot
> to put "option MSDOSFS" in my kernel config (and we always build our
> systems with no .ko modules at all).
>
> -- Ian
>
> diff -r 0e647646c002 sbin/newfs_msdos/newfs_msdos.c
> --- sbin/newfs_msdos/newfs_msdos.c.orig	Thu Sep 29 08:39:38 2011 -0600
> +++ sbin/newfs_msdos/newfs_msdos.c	Sun Oct 16 10:40:07 2011 -0600
> @@ -98,7 +98,7 @@ static const char rcsid[] =
>   struct bs {
>       u_int8_t bsJump[3];		/* bootstrap entry point */
>       u_int8_t bsOemName[8];		/* OEM name and version */
> -};
> +} __packed;
>
>   struct bsbpb {
>       u_int8_t bpbBytesPerSec[2];		/* bytes per sector */
> @@ -113,7 +113,7 @@ struct bsbpb {
>       u_int8_t bpbHeads[2];		/* drive heads */
>       u_int8_t bpbHiddenSecs[4];		/* hidden sectors */
>       u_int8_t bpbHugeSectors[4];		/* big total sectors */
> -};
> +} __packed;
>
>   struct bsxbpb {
>       u_int8_t bpbBigFATsecs[4];		/* big sectors per FAT */
> @@ -123,7 +123,7 @@ struct bsxbpb {
>       u_int8_t bpbFSInfo[2];		/* file system info sector */
>       u_int8_t bpbBackup[2];		/* backup boot sector */
>       u_int8_t bpbReserved[12];			/* reserved */
> -};
> +} __packed;
>
>   struct bsx {
>       u_int8_t exDriveNumber;		/* drive number */
> @@ -132,7 +132,7 @@ struct bsx {
>       u_int8_t exVolumeID[4];		/* volume ID number */
>       u_int8_t exVolumeLabel[11]; 	/* volume label */
>       u_int8_t exFileSysType[8];		/* file system type */
> -};
> +} __packed;
>
>   struct de {
>       u_int8_t deName[11];	/* name and extension */
> @@ -142,7 +142,7 @@ struct de {
>       u_int8_t deMDate[2];	/* creation date */
>       u_int8_t deStartCluster[2];	/* starting cluster */
>       u_int8_t deFileSize[4];	/* size */
> -};
> +} __packed;
>
>   struct bpb {
>       u_int bpbBytesPerSec;		/* bytes per sector */
>
>
>