I agree with this implementation. Though WFI seems make no sense for a
userspace program, we should not have assumption that the userspace
program will not use this instruction.
It seems ARM manual does not defined the implementation of function
EnterLowPowerState(); However, before executing this instruction, there
are some checks like below:
if PSTATE.EL == EL0 then
// Check for traps described by the OS which may be EL1 or EL2.
AArch32.CheckForWFxTrap(EL1, FALSE);
I am not sure whether it is complex/required to implement this in QEMU.
Maybe patch the WFI as a NOP looks like the best idea at this moment.
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https://bugs.launchpad.net/bugs/1926759
Title:
WFI instruction results in unhandled CPU exception
Status in QEMU:
Confirmed
Bug description:
Hi
I refer to the WFI instruction. The bytecode is 0xe320f003. After the
execution, qemu exit with the following crash log.
qemu: unhandled CPU exception 0x10001 - aborting
R00=00000001 R01=40800b34 R02=40800b3c R03=000102ec
R04=00010a28 R05=00010158 R06=00087460 R07=00010158
R08=00000000 R09=00000000 R10=00085b7c R11=408009f4
R12=40800a08 R13=408009f0 R14=0001057c R15=000102f8
PSR=60000010 -ZC- A usr32
qemu:handle_cpu_signal received signal outside vCPU context @
pc=0x7f5c21d0fa12
WFI aims to enter a low-power state and wait for interrupt. The raised
exception seems not a right behavior. I can provide a testcase if you
needed. Many thanks.
Regards
Muhui
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