All elements in the Switch's boot chain up to the kernel have the ability to issue a system panic.

Panics are handled by writing a panic code in the PMC_SCRATCH200 register and requesting a reboot by programming a dedicated hardware watchdog (WDT4). The bootloaders and the Secure Monitor are able to do this right away, but the kernel must invoke the Panic SMC.

When the system reboots, the encrypted bootloader checks if the reset was requested by the watchdog (PMC_RST_STATUS register is set to 0x01) and parses the panic code stored in PMC_SCRATCH200.

If a panic did occur, the Switch will paint the main screen with a solid color and halt execution.

Structure

Bits Field
31-28 Blue value
27-24 Green value
23-20 Red value
19-0 Description

The blue, green and red values are nibbles which represent the color that will fill the panic screen. Each nibble is duplicated to form a full byte before writing the final color to the display's MMIO.

Panic colors

Different colors are used to represent panic events coming from different execution levels within the system.

Color Value Level
0x000000 Default
0x0000FF Kernel
0x00FFFF Secure Monitor (general errors)
0x00AAFF Secure Monitor (deep sleep)
0xAA00FF Bootloader (general errors)
0xFFFFAA Bootloader (wrong bootloader)
0xFFAA00 GPU

Panic codes

While any combination of panic colors and codes is possible, several panic codes are specifically tied to a certain execution level.

Value Level Description
0x0 Any No information
0x1 Kernel Package2 signature verification failed
0x2 Kernel Package2 meta verification failed
0x3 Kernel Package2 version check failed
0x4 Kernel Package2 payload verification failed
0x5 Secure Monitor Unknown SMC
0x6 Secure Monitor Unknown Abort
0x7 Secure Monitor Invalid CPU context
0x8 Secure Monitor Invalid SE state
0x9 Secure Monitor CPU is already awake
0x10 Any Unknown exception
0x20 Bootloader Rebooting into SafeMode
0x21 Bootloader Rebooting for anti-downgrade
0x30 Bootloader General bootloader error
0x31 Bootloader Invalid DRAM ID
0x32 Bootloader Invalid size
0x33 Bootloader Invalid argument
0x34 Bootloader Bad GPT
0x35 Bootloader Failed to boot SafeMode
0x36 Bootloader-color [4.0.0+]
0x40 Kernel Show error called (kernel panic)