Re: [Qemu-devel] Virtual FAT disk images error, can somebody help me , thank you !

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

On Thu, Mar 08, 2012 at 02:11:33PM +0800, Zhi Hui Li wrote:
> when I use the command :
> 
> 1: mkdir /my_directory
> 
> 2: qemu linux.img -fda fat:floppy:/my_directory
> 
> when I write to the floppy(just "mkdir test.dir"  in the floppy),
> the error occur:
> 
> "FLOPPY ERROR: fdctrl_transfer_handler: writing sector 1"
> 
> and nothing is written to the /my_directory.
> 
> I don't know why?

Although the error comes from hw/fdc.c code it's probably originates in
block/vvfat.c:vvfat_write(), because fdc.c is calling bdrv_write() and
reports an error if that function fails.

I suggest adding printfs or using gdb.  The only two returns that have
no fprintf(stderr, ...) are:

/* Check if we're operating in read-only mode */
if (s->qcow == NULL) {
    return -EACCES;
}

and

if (sector_num < s->first_sectors_number)
    return -1;

Perhaps one of these is failing?

Stefan