Add u-mode feature #7
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andelf
reviewed
Oct 31, 2024
| // Qingke V2A, V2C | ||
| // (does not have user mode) |
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non-blocking: build.rs can be used to check illegal feature combinations. I don't know if static_assert is avaliable.
Codetector1374
approved these changes
Oct 31, 2024
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Adds a new cargo feature
u-modeto qingke-rt. This chooses if main is ran at privilege mode M or U.This does change the default behaviour to M (cooould change this), but the only thing U-mode would stop is, in main/thread mode only (wouldn't do anything to stop ISRs which always run in M-mode) an M-mode CSR access or M-mode instruction like MRET, but these are unsafe already. Also, Qingke V2 never had U-mode to begin with.
My usecase is for a bootloader where mstatus and MRET are used in order to jump to the application while disabling interrupts sort of like the reset handler does, so it has to run in M-mode.