Akarys
Inkling
- Joined
- Jan 30, 2024
- Messages
- 4
Tech fun fact of the day related to the Nintendo Switch: Firmware fuses!
The System-On-a-Chip (SoC, basically a chip packing together CPU, GPU, RAM and other utilities making up the system) inside the Switch, the Nvidia Tegra, has a quite special unit of storage that use actual fuses! Yes, we're talking about fuses that function similarly to the ones inside your house, they let current through but blow up if too much is provided, severing the connection. What does this unit does? It provides read-write memory, just like RAM inside your computer, but it can only be written to *once*, as it blows up said fuses to write data, which can't be reverted.
When the firmware (more or less the operating system) of your Nintendo Switch is updated, the console will write to that unit, blowing up as many fuses as needed to match the current version. This is then checked when the console boots, if the current firmware version is lesser than the number of fuses blown up, it means you have tried to revert a firmware update in some way, and the console will refuse to start.
Why does Nintendo do that? They use firmware updates to patch "critical vulnerabilities", aka. vulnerabilities that allow homebrewing. This is an additional layer of protection to prevent any shenanigans from happening. Sadly for them, the main exploit used in "Switch v1" is based on an *hardware vulnerability*, something due to the physical structure of the components inside the Switch, impossible for them to patch through an update. The exploits also runs before fuses are checked, rendering them completely useless here.
The System-On-a-Chip (SoC, basically a chip packing together CPU, GPU, RAM and other utilities making up the system) inside the Switch, the Nvidia Tegra, has a quite special unit of storage that use actual fuses! Yes, we're talking about fuses that function similarly to the ones inside your house, they let current through but blow up if too much is provided, severing the connection. What does this unit does? It provides read-write memory, just like RAM inside your computer, but it can only be written to *once*, as it blows up said fuses to write data, which can't be reverted.
When the firmware (more or less the operating system) of your Nintendo Switch is updated, the console will write to that unit, blowing up as many fuses as needed to match the current version. This is then checked when the console boots, if the current firmware version is lesser than the number of fuses blown up, it means you have tried to revert a firmware update in some way, and the console will refuse to start.
Why does Nintendo do that? They use firmware updates to patch "critical vulnerabilities", aka. vulnerabilities that allow homebrewing. This is an additional layer of protection to prevent any shenanigans from happening. Sadly for them, the main exploit used in "Switch v1" is based on an *hardware vulnerability*, something due to the physical structure of the components inside the Switch, impossible for them to patch through an update. The exploits also runs before fuses are checked, rendering them completely useless here.
