Hi,

I have the same problem here with cgminer 4.5.0.

Here is my config :

R-pi B with Raspbian v7.6
Linux kernel : Linux raspberrypi 3.12.22+ #691 PREEMPT Wed Jun 18 18:29:58 BST 2014 armv6l GNU/Linux
cgminer compiled with : ./configure --prefix=/opt/cgminer-4.5.0 --enable-icarus

Everything worked fine for about a month with a rockminer R-Box (and cgminer 4.4.2).

Now I added 2 more of these r-boxes on the same USB port (via a powered USB hub) and it fails either with a Segmentation Fault or "Failed to sem_post errno=38 cgsem=0x0xb473e6b0 in usbutils.c transfer_callback():2774"

I already have changed the semaphore values :

kernel.sem = 2048       2097152 2048    1024

but I don't think that's the point.

I see a lot of USB errors in /var/log/messages : "Aug  5 10:40:23 raspberrypi kernel: [42515.751676] usb 1-1.2.3: reset full-speed USB device number 51 using dwc_otg"

So I'll try to connect one of the r-boxes to the other USB port on the pi to see if it changes anything.

Any other ideas I could try ?