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The hidden JTAG in a Qualcomm/Snapdragon device’s USB port

(www.linaro.org)
242 points denysvitali | 1 comments | 30 Jun 25 18:34 UTC | HN request time: 0.208s | source
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dazhbog ◴[30 Jun 25 20:28 UTC] No.44427489[source]▶
So just to get this straight, Qualcomm has a piece of custom silicon, as a peripheral controlled by registers, that when enabled reroutes the ARMs USB pins through it (adding a USB hub in the middle), and on that hub it adds a SWD programmer and a serial port that connect back to the ARM core's IOs? Amazing!
replies(2): >>44427681 #>>44429958 #
1. ethan_smith ◴[01 Jul 25 02:14 UTC] No.44429958[source]▶
This USB-based debug approach is becoming standard practice across SoC vendors (MediaTek's preloader, Apple's special cables) as it eliminates dedicated debug headers while maintaining controlled access through eFuse-gated authentication.