OK I'm completely baffled.
I have explicitly removed all rtlwifi/ firmware files from the root
filesystem and yet the usb dongle still works, even after a power
cycle. How can it possibly be getting its firmware file????????
Here are the relevant kernel messages. There is no file
rtl8192cufw.bin anywhere for the kernel to find...
root@30046:~# ls -l /lib/firmware/rtlwifi/
total 0
I have ensured there is no *OTHER* route to the internet such that the
driver (or udev) can magically get the firmware file from the
internet...
Here's other info that may be useful...
root@30046:~# zcat /proc/config.gz | grep FIRM
CONFIG_PREVENT_FIRMWARE_BUILD=y
CONFIG_FIRMWARE_IN_KERNEL=y
CONFIG_EXTRA_FIRMWARE="am335x-pm-firmware.elf
am335x-bone-scale-data.bin am335x-evm-scale-data.bin
am43x-evm-scale-data.bin"
CONFIG_EXTRA_FIRMWARE_DIR="firmware"
# CONFIG_LIBERTAS_THINFIRM is not set
# CONFIG_FIRMWARE_MEMMAP is not set
# CONFIG_TEST_FIRMWARE is not set
root@30046:~# cat /proc/version
Linux version 4.1.19-bone20 (dash@DaveDesktop) (gcc version 5.4.0
20160609 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.4) ) #2 Tue Oct 3
17:25:35 CDT 2017
root@30046:~# lsusb
Bus 001 Device 002: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un
802.11n Wireless Adapter [Realtek RTL8188CUS]
... ifconfig
wlan0 Link encap:Ethernet HWaddr 74:da:38:61:f1:2c
inet addr:192.168.10.31 Bcast:192.168.10.255 Mask:255.255.255.0
inet6 addr: fe80::76da:38ff:fe61:f12c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:509 errors:0 dropped:0 overruns:0 frame:0
TX packets:146 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:60812 (59.3 KiB) TX bytes:16365 (15.9 KiB)
[ 9.663796] rtl8192cu: Chip version 0x10
[ 9.745394] cfg80211: Calling CRDA to update world regulatory domain
[ 9.844311] random: nonblocking pool is initialized
[ 9.877851] rtl8192cu: MAC address: 74:da:38:61:f1:2c
[ 9.877883] rtl8192cu: Board Type 0
[ 9.877989] rtl_usb: rx_max_size 15360, rx_urb_num 8, in_ep 1
[ 9.878098] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw_TMSC.bin
[ 9.878249] usb 1-1: Direct firmware load for
rtlwifi/rtl8192cufw_TMSC.bin failed with error -2
[ 9.889781] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
[ 9.890862] usbcore: registered new interface driver rtl8192cu
[ 9.897667] usb 1-1: Direct firmware load for
rtlwifi/rtl8192cufw.bin failed with error -2
[ 9.906030] rtlwifi: Loading alternative firmware rtlwifi/rtl8192cufw.bin
[ 9.906037] rtlwifi: Firmware rtlwifi/rtl8192cufw_TMSC.bin not available
[ 11.316476] rtl8192cu: MAC auto ON okay!
[ 11.333847] rtl8192cu: Tx queue select: 0x05
[ 12.364722] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[ 12.905367] cfg80211: Calling CRDA to update world regulatory domain
[ 13.413043] rtl8192cu: MAC auto ON okay!
[ 13.430371] rtl8192cu: Tx queue select: 0x05
[ 15.795679] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[ 16.065356] cfg80211: Calling CRDA to update world regulatory domain
[ 19.225333] cfg80211: Calling CRDA to update world regulatory domain
[ 21.582749] wlan0: authenticate with 70:4d:7b:1d:91:40
[ 21.600676] wlan0: send auth to 70:4d:7b:1d:91:40 (try 1/3)
[ 21.605390] wlan0: authenticated
[ 21.615431] wlan0: associate with 70:4d:7b:1d:91:40 (try 1/3)
[ 21.667523] wlan0: RX AssocResp from 70:4d:7b:1d:91:40 (capab=0x411
status=0 aid=5)
[ 21.669000] wlan0: associated
[ 21.669671] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[ 22.385320] cfg80211: Calling CRDA to update world regulatory domain
[ 25.545336] cfg80211: Calling CRDA to update world regulatory domain
[ 28.705312] cfg80211: Calling CRDA to update world regulatory domain
[ 31.865335] cfg80211: Calling CRDA to update world regulatory domain
[ 35.025348] cfg80211: Exceeded CRDA call max attempts. Not calling CRDA
Thanks!!!!!!
-Dave
On 10/25/17, Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote:
> On 10/25/2017 01:43 PM, David Ashley wrote:
>> I'm trying to understand how the linux kernel loads RTL8188CUS firmware
>> rtlwifi: Loading alternative firmware rtlwifi/rtl8192cufw.bin
>> when that file isn't available anywhere in my embedded system's
>> filesystem.
>>
>> Basically I'm trying to understand the theory. We have a product that
>> is making use of the device
>>
>> Bus 001 Device 007: ID 7392:7811 Edimax Technology Co., Ltd
>> EW-7811Un802.11n Wireless Adapter [Realtek RTL8188CUS]
>>
>> It has not been especially reliable. I've never provided firmware
>> files for the device in the root filesystem. I've started to pay
>> attention to the kernel error messages. Now the kernel drivers seem to
>> be loading the rtlwifi/rtl8192cufw_TMSC.bin file and I'm trying to
>> understand if this is actually working, if it makes any difference in
>> reliability...
>>
>> It's like I can't figure out how the usb dongle even worked without
>> its firmware file...
>>
>> My working theory is that the usb dongle comes from the factory with a
>> hardcoded firmware file (rtlwifi/rtl8192cufw.bin) but it is buggy or
>> inferior. And the performance and reliability can be improved if the
>> driver successfully manages to load the rtl8192cufw_TMSC.bin file. I
>> don't know if the firmware load persists across a power cycle (my
>> assumption is it doesn't).
>
> There is NO firmware coded by the factory in the device. It only has enough
>
> intelligence to load the real firmware. The exact file that it loads is
> determined by the model. If you provide the appropriate section of the
> output of
> dmesg where the above firmware messages occur, and a file listing of
> /lib/firmware/rtlwifi/, I can tell you what firmware is being loaded.
>
> No, firmware will not persist across a power failure.
>
> The driver has never been particularly reliable, and the USB group at
> Realtek
> seems not to care. You might try their other driver, but you will be on your
>
> own, as I will not support that particular piece of ****.
>
> Please reply to all on any followups.
>
> Larry
>
>
