He estado usando CgMiner 3.4.1 desde finales de septiembre. Puede ver mis cuatro USB Block Erupters y funciona:

 cgminer version 3.4.1 - Started: [2013-11-20 07:48:07]
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 (5s):1.223G (avg):978.4Mh/s | A:18  R:0  HW:1  WU:17.4/m
 ST: 2  SS: 0  NB: 1  LW: 37  GF: 0  RF: 0
 Connected to stratum.bitcoin.cz diff 3 with stratum as user joesmith
 Block: 00070bedfe64cbc8...  Diff:609M  Started: [07:48:07]  Best share: 124
--------------------------------------------------------------------------------
 [P]ool management [S]ettings [D]isplay options [Q]uit
 AMU 0:                | 307.2M/327.5Mh/s | A:12 R:0 HW:0 WU:10.0/m
 AMU 1:                | 267.8M/314.6Mh/s | A: 0 R:0 HW:0 WU: 2.5/m
 AMU 2:                | 280.3M/322.7Mh/s | A: 6 R:0 HW:0 WU: 3.7/m
 AMU 3:                | 127.4M/308.9Mh/s | A: 3 R:0 HW:1 WU:10.5/m
--------------------------------------------------------------------------------

 [2013-11-20 07:48:43] Accepted 1326b92d Diff 13/3 AMU 0
 [2013-11-20 07:48:47] Accepted 3e086003 Diff 4/3 AMU 0
 [2013-11-20 07:48:58] Accepted 487047eb Diff 3/3 AMU 3

Pero regularmente falla con un desbordamiento de pila .

Hace aproximadamente un mes intenté actualizar a CgMiner 3.6 , pero no puedo encontrar mis dispositivos USB:

 cgminer version 3.6.0 - Started: [2013-11-20 07:49:52]
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 (5s):0.000 (avg):0.000h/s | A:0  R:0  HW:0  WU:0.0/m
 ST: 2  SS: 0  NB: 1  LW: 2  GF: 0  RF: 0
 Connected to stratum.bitcoin.cz diff 3 with stratum as user joesmith
 Block: 00070bedfe64cbc8...  Diff:609M  Started: [07:49:52]  Best share: 0
--------------------------------------------------------------------------------
 [P]ool management [S]ettings [D]isplay options [Q]uit
--------------------------------------------------------------------------------

 [2013-11-20 07:49:49] Started cgminer 3.6.0
 [2013-11-20 07:49:49] Loaded configuration file cgminer.conf
 [2013-11-20 07:49:51] No devices detected!
 [2013-11-20 07:49:51] Waiting for USB hotplug devices or press q to quit
 [2013-11-20 07:49:51] Probing for an alive pool
 [2013-11-20 07:49:52] Pool 0 difficulty changed to 3
 [2013-11-20 07:49:52] Network diff set to 609M

Así que volví a 3.4.1vivir con los bloqueos semidiarios y tener que recordar reiniciar CgMiner. Esta mañana probé CgMiner 3.8 , con la esperanza de que solucionaran su incapacidad para ver USB Block Eruptors (y el desbordamiento de pila). Desafortunadamente, todavía no ve los dispositivos USB:

 cgminer version 3.8.0 - Started: [2013-11-20 07:44:46]
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 (5s):0.000 (avg):0.000h/s | A:0  R:0  HW:0  WU:0.0/m
 ST: 2  SS: 0  NB: 1  LW: 16  GF: 0  RF: 0
 Connected to stratum.bitcoin.cz diff 1 with stratum as user joesmith
 Block: 70bedfe6...  Diff:609M  Started: [07:44:46]  Best share: 0
--------------------------------------------------------------------------------
 [P]ool management [S]ettings [D]isplay options [Q]uit
--------------------------------------------------------------------------------

 [2013-11-20 07:44:42] Started cgminer 3.8.0
 [2013-11-20 07:44:42] Loaded configuration file cgminer.conf
 [2013-11-20 07:44:44] AMU 0 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
 [2013-11-20 07:44:44] FAIL: USB get_lock not found (3:2)
 [2013-11-20 07:44:44] FAIL: USB remove not already in use (3:2)
 [2013-11-20 07:44:45] No devices detected!
 [2013-11-20 07:44:45] Waiting for USB hotplug devices or press q to quit
 [2013-11-20 07:44:45] Probing for an alive pool
 [2013-11-20 07:44:46] Pool 0 difficulty changed to 3
 [2013-11-20 07:44:46] Network diff set to 609M
 [2013-11-20 07:45:14] Pool 0 difficulty changed to 1
 [2013-11-20 07:45:14] Stratum from pool 0 requested work restart
 [2013-11-20 07:45:14] Stratum from pool 0 requested work restart

Así que, una vez más, volví a CgMiner 3.4.1.

¿Qué rompieron después de CgMiner 3.4 y cómo lo soluciono?

WinUSB

Solo para adelantarme a las personas que podrían sugerirlo, en lugar de ofrecer alguna información, volví a ejecutar zadiag 2.0.1.162 (actualizado el 20/11/2013) y "reinstalé" el controlador WinUSB para mis dispositivos USB (y reinicié)

Sin efecto.

¿Qué está haciendo CgMiner 2.8 mal que CgMiner 2.4 hizo bien?

Editar : Usando el propio VCP de Silicon Labs (controlador de puerto COM virtual):

da el error (en BfgMiner):

usb_devinfo_scan: Error opening device: LIBUSB_ERROR_NOT_SUPPORTED

En CgMiner da:

USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 1:3
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:3
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:2
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:6
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:8
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:10
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:11
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:12
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 3:13
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 6:2
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 8:3
USB init, open device failed, err -12, you need to install a WinUSB driver for - AMU device 8:1

Así que lo cambié probando cada controlador con algunos de los mineros. Tres usan el controlador libusb-win32 , tres usan el controlador libusbx.org y el resto usa el controlador Silicon Labs CP210x USB to UART Bridge :

Tanto CgMiner como BfgMiner no detectan dispositivos.