[SLOF] [PATCH] fat-files: Fix bug with root-entries = 0 on certain FAT32 file systems

Thomas Huth thuth at redhat.com
Thu Dec 3 07:42:09 AEDT 2015

On 02/12/15 16:39, Thomas Huth wrote:
> The maximum number of root directory entries can be zero on
> certain FAT32 file systems. In this case, we've got to read
> the cluster number of the root directory from the extended BPB
> instead. See also the following URL for details:
> https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system#BPB20_OFS_06h

Forgot to say: With that patch, I was able to boot from a pass-through
USB stick that was formatted with FAT32.
However, there are some additional messages from libusb showing up:

Scanning USB
  XHCI: Initializing
ptr 0x7E4E8019 desc_type 48
ptr 0x7E4E8026 desc_type 48
    USB Storage
       SCSI: Looking for devices
          101000000000000 DISK     : "SanDisk Ultra Fit 1.00"

... if I get that "desc_type 48" right, this means that libusb can not
handle "SuperSpeed Endpoint Companion Descriptor" yet? Is this something
to worry about or just harmless debug messages?


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