On Tue, Mar 22, 2022 at 04:59:31PM -0400, Sean Anderson wrote:
If a debugger is not attached to U-Boot, semihosting calls will raise a synchronous abort exception. Try to catch this and disable semihosting so we can e.g. use another uart if one is available. In the immediate case, we return an error, since it is not always possible to check for semihosting beforehand (debug uart, user-initiated load command, etc.)
We handle all possible semihosting instructions, which is probably overkill. However, we do need to keep track of what instruction set we're using so that we don't suppress an actual error.
A future enhancement could try to determine semihosting capability by inspecting the processor state. There's an example of this at [1] for RISC-V. The equivalent for ARM would inspect the monitor modei enable/select bits of the DSCR. However, as the article notes, an exception handler is still helpful in order to catch disconnected debuggers.
[1] https://tomverbeure.github.io/2021/12/30/Semihosting-on-RISCV.html#avoiding-...
Signed-off-by: Sean Anderson sean.anderson@seco.com
Applied to u-boot/next, thanks!