Some updates, second can1 interface doesn’t come up after building and installing the patched module, getting this error:
mcp25xxfd spi1.0 (unnamed net_device) (uninitialized): Failed to detect MCP2517FD (osc=0x00000000).
dump of relevant data
pi@raspberrypi:~ $ dmesg | grep spi
[ 6.200302] spi_master spi0: will run message pump with realtime priority
[ 6.222181] mcp25xxfd spi0.0 can0: MCP2517FD rev0.0 (-RX_INT +MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD m:20.00MHz r:18.50MHz e:18.18MHz) successfully initialized.
[ 6.223641] spi_master spi1: will run message pump with realtime priority
[ 6.262628] mcp25xxfd spi1.0 (unnamed net_device) (uninitialized): Failed to detect MCP2517FD (osc=0x00000000).
pi@raspberrypi:~ $ sudo ifconfig can0
can0: flags=128 mtu 16
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 10 (UNSPEC)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 167pi@raspberrypi:~ $ sudo ifconfig can1
can1: error fetching interface information: Device not found
pi@raspberrypi:~ $ uname -an
Linux raspberrypi 4.19.118-v7+ #2 SMP Mon Jul 27 19:26:18 BST 2020 armv7l GNU/Linux
pi@raspberrypi:~ $