alt Hacker NewsI’m not following. Why would it be helpful to check how many fuses had been blown? And how could you have more blown fuses than you’re supposed to?
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Here's an excerpt about the anti-rollback feature from Nvidia's docs on how the Tegra X1 SoC in the switch 1 boots [0] (called Tegra210 in the document)
> By default, the boot ROM will only consider bootloader entries with a version field that matches the version field of the first entry, and will stop iterating through the entries is a mismatch is found. The intent is to ensure that if some subset of the bootloader entries are upgraded, and hence the version field of their entries is modified, then the boot ROM will only boot the most recent version of the bootloader. This prevents an accidental rollback to an earlier version of the bootloader in the face of boot memory read errors, corruption, or tampering. Observe that this relies on upgraded bootloader entries being placed contiguously at the start of the array.
[0] https://http.download.nvidia.com/tegra-public-appnotes/tegra...
Firmware v1 requires a switch with zero fuses blown.
Firmware v2 requires a switch with no more than one fuse blown and blows the first fuse.
If you install v2, you can't install v1.
Nintendo can make 22 firmware releases that disallow rollback.