Zephyr Shell Console and Logging Targeting Isolated Different Device Interfaces

[bob2oneil]

I would like to split the Zephyr SHELL logging from general logging vla LOG_X into different physical interface backends.

Example of this might be 2 UARTS, 1 UART plus a Telnet Session for the shell, or 2 Telnet session operating on different TCP ports.

• The logging output would be output only on 1 interface.
• The shell interface without be input output as a user console on a different interface.

The purpose of this isolation is to keep standard logging, which can be a continuous stream, from overwriting the menus and results from the shell interface.

For 2 Telnet sessions:

1. For the case of the 2 Telnet configuration, one session would acts as the logging out, presumably the user would log into and request either a dump of historic log output, presumably captured to memory, or would just start the log dumping that occurred at that time forward, with the ability to shut it down upon entry of some keystroke.
2. The other more conventional Telnet session, assuming Telnet is used for both roles, would be the interactive user console Zephyr shell.

So notionally, I might need the option of capture log output to memory for one modality, or dumping log content onto the floor up until the point that the logging output is enabled.

Any general recommendations or direction on this redirection of both the logging output and the Zephyr shell to different isolated interfaces as described?

If there was a way of multiplexing the console and log output, multiplexing them, which I am not sure how that would work where the log content would not overwrite the shell menus, details on that would be much appreciated.

For a 2 Uart implementation, it might seem that only the following device tree entries are required?
What about network Telnet interfaces working on different ports?

chosen {
		zephyr,console = &uart0;
		zephyr,shell-uart = &uart1;
		zephyr,uart-mcumgr = &uart0;
		zephyr,flash = &flash0;
		zephyr,entropy = &rng;
		zephyr,flash-controller = &flashcontroller0;
		zephyr,ec-host-interface = &hcp;
	};

The Telnet sample does a good job of showing the shell being targeted towards a Telnet session.
However, I am unable to get logging to isolate device target as the UART interface without it also targeting the Telnet session using this sample and making a few modifications as follows:

void main(void)
{
	struct net_if *iface = net_if_get_default();

	LOG_INF("Starting Telnet sample");

	setup_ipv4(iface);

	setup_dhcpv4(iface);

	setup_ipv6(iface);

	for (unsigned int i = 0; i < (unsigned)-1; i++)
	{
		printk("[%d] Telnet sample log output from printk()\n", i);

		LOG_INF("[%d] Telnet sample log output", i);

		k_msleep(SLEEPTIME);
	}
}

The kernel configuration as follows, and this effort targets the native_posix_64 board target.

CONFIG_PRINTK=y

CONFIG_NETWORKING=y
CONFIG_NET_IPV6=y
CONFIG_NET_IPV4=y
CONFIG_NET_ARP=y
CONFIG_NET_UDP=y
CONFIG_NET_TCP=y

CONFIG_NET_DHCPV4=n

CONFIG_NET_IF_UNICAST_IPV6_ADDR_COUNT=3
CONFIG_NET_IF_MCAST_IPV6_ADDR_COUNT=2
CONFIG_NET_MAX_CONTEXTS=10
CONFIG_NET_PKT_TX_COUNT=20
CONFIG_NET_BUF_TX_COUNT=50

CONFIG_TEST_RANDOM_GENERATOR=y

CONFIG_INIT_STACKS=y

CONFIG_NET_BUF_LOG=n
CONFIG_NET_LOG=n

CONFIG_NET_CONFIG_SETTINGS=y
CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8::1"
CONFIG_NET_CONFIG_MY_IPV4_ADDR="192.0.1.1"

CONFIG_NET_SHELL=y
CONFIG_KERNEL_SHELL=y
CONFIG_SHELL_BACKEND_TELNET=y
CONFIG_LOG=y
CONFIG_LOG_BACKEND_UART=y
CONFIG_NET_STATISTICS=y

# Debug Options for debugging
CONFIG_DEBUG_OPTIMIZATIONS=y

Walking through the code into LOG_INF() into method log_generic() the <shell_backend_telnet> device/value is positive allowing all log output to likewise target this interface.

[bob2oneil]

This item was discussed and closed as item #36057, "Zephyr Shell Console and Logging Targeting Isolated Different Device Interfaces". I was missing a kernel configuration parameter.