If you're using the esp-open-sdk, create a Makefile.local similar to the following:
OPENSDK := /path/to/esp-open-sdk
PATH := $(OPENSDK)/xtensa-lx106-elf/bin:$(PATH)
Otherwise you'll need to set the paths of the SDK and toolchain to use manually:
SDK_BASE := /path/to/esp_iot_sdk_v1.1.2
ESPTOOL := /path/to/esptool.py
PATH := /path/to/xtensa-lx106-elf/bin:$(PATH)
USE_OPENSDK := no
Additional settings you may want to change in your Makefile.local:
ESPPORT := /dev/ttyUSB0
ESPBAUD := 921600
#SPI flash size, in K
ESP_SPI_FLASH_SIZE_K := 512
#0: QIO, 1: QOUT, 2: DIO, 3: DOUT
ESP_FLASH_MODE := 0
#0: 40MHz, 1: 26MHz, 2: 20MHz, 0xf: 80MHz
ESP_FLASH_FREQ_DIV := 0
Then just run make, make flash or even make run.
UART0 and UART1 both run at 115200 baud. A REPL interface for wireless configuration runs on UART0 and debug output is on UART1.