I guess I found a fix to make working again AirDrop (from Catalina Finder) on unsupported Catalina Mac
Premise: I have noticed that starting from Catalina, AirDrop feature requires a Bluetooth 4.0 device (internal or USB) in order to be showed in the Finder, and to detect the other Mac and iOS devices connected on the same wifi network.
While till Mojave it was still possible to find older Mac and iOS devices even without a BT 4.0 dongle.
Before start, this method:
https://apple.lib.utah.edu/airdrop-how-to-enable-on-os-x-mavericks-via-ethernet/
doesn't worked on Catalina, it just enables a Finder AirDrop icon without any functionality, and more over (if worked) was only for ethernet connected Mac, not Wifi Mac/devices.
Here is how I made and understood "my fix":
First of all I observed that both on my MacBookPro2010 (i5 cpu dualGPUs) and MacBook7,1 (core2duo cpu Nvidia) the driver used for my Wifi Airport Broadcom was this:
kextstat | grep AirPort
com.apple.driver.AirPort.Brcm4331
Then looking at the "Continuity Activation Tool" I understood that the allowed Wifi Broadcom driver to support AirDrop over a BT 4.0 device is this
com.apple.driver.AirPort.Brcm4360
So using a couple of BT 4.0 USB dongle, with "continuityactivationtool" I have attempted to partial fix whitelisting (without touching the IOBluetooth) inside the AirPortBrcm4360 binary file the machine boardID, but it can also be done manually, open Terminal and copy/paste:
ioreg -l | grep "board-id" | awk -F\" '{print $4}'
from output get your boardID for example:
Mac-F22C89C8 (MacBook7,1 mid 2010)
And opening inside IO80211Family.kext the "AirPortBrcm4360 binary exec" using an hex editor (or other method) whitelist this boardID from "ascii to hex" searching for "
Mac-" in hex becomes "
4d 61 63 2d".
Typically the first occurrence should be suffice, but I've swapped all the other encountered for safety and to catch any possible additional function adding only that boardID (example picture attached).
Since the older machine boardID numbers are shorter, after added your (ascii-to-hex) boardID add an octet of "00" (example picture attached).
Response: it worked!
I attach for now only a "fix" tested and working for MacBook7,1 mid 2010 , and before replacing the attached kext, from Catalina Terminal:
sudo mount -uw / ; killall Finder ; open /S*/L*/E*/IO80211Family.kext/C*/P*/
Then back to Terminal and type:
sudo chown -R 0:0 /S*/L*/E*
sudo chmod -R 755 /S*/L*/E*
sudo kextcache -i /
I attached also the non-patched AirPortBrcm4331.kext because I discovered that Wifi Airport Broadcom can use both 4331 and 4360 , in fact the "PCI Match device id" for this Broadcom wifi is present (from HighSierra, Mojave) in both the driver Info.plist : <string>pci14e4,4353</string>
So if my patch for some reason doesn't work on your machine your wifi will use the other driver, but I repeat the patch I posted is only for MacBook7,1 mid 2010.
I add also another for MacBookPro6,2 15" mid 2010 dualGPUs (in the specified folder).
The file attached allows to enable the AirDrop feature on Catalina Finder, and if you plug a Bluetooth 4.0 dongle it should work too and detect all the devices inside the same wifi network (with "discovered by Everyone" checked).
