We have ported the FreeBSD USB stack to my employers proprietary RTOS.  The
code was taken from the MAIN branch a little while after RELENG_8_BP tag was

I'm trying to read data from the following mass storage device umass0:

usbus0: EHCI version 1.0
usbus0: 480Mbps High Speed USB v2.0
ugen0.1: <Intel EHCI root HUB> at usbus0
uhub0: <Intel EHCI root HUB, class 9/0, rev 2.00/1.00, addr 1> on usbus0
uhub0: 2 ports with 2 removable, self powered
ugen0.2: <vendor 0x8087 product 0x0024> at usbus0
uhub1: <vendor 0x8087 product 0x0024, class 9/0, rev 2.00/0.00, addr 2> on
uhub1: 8 ports with 8 removable, self powered
ugen0.3: <ATP Electronics ATP IG eUSB> at usbus0
umass0: <ATP Electronics ATP IG eUSB, class 0/0, rev 2.00/11.00, addr 3> on
umass0:  SCSI over Bulk-Only; quirks = 0x4800

Reading data one frame per transfer works.  For example, if I want to read
512 bytes that is physically contiguous and is placed in a single frame,
that works fine.

However, when attempting to read 1024 bytes, that is not physically
contiguous, using 3 frames for the same transfer, I get USB_ERR_STALLED.  I
have the frames setup as follows:
frame[0] = 200 bytes
frame[1] = 512 bytes
frame[2] = 312 bytes

Here's what my code looks like to do this:

usb_frcount_t frindex = 0;                                                      
for ( Storage::Byte_device::Scatter_gather *sg_entry =
scb->SC_SG_List->In_progress_SGs(); sg_entry; sg_entry=sg_entry->SG_Link )      
    usbd_xfer_set_frame_data( xfer, frindex++, reinterpret_cast<void
*>(sg_entry->SG_Virtual_address), sg_entry->SG_Length );                      
usbd_xfer_set_frames(xfer, frindex);                                            

Note, in usbd_transfer_setup, I have set the maximum number of frames to 128
for this transfer (UMASS_T_BBB_DATA_READ). 

Question: Is it possible to transfer 1024 bytes using the method described


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