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panic on panic: improve behaviour description

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Ciro Santilli 六四事件 法轮功
2019-05-08 00:00:00 +00:00
parent 3d83206461
commit 18ca0b3c9c
1 changed files with 13 additions and 5 deletions
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README.adoc
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@@ -3798,6 +3798,8 @@ Simulated exit code not 0! Exit code is 1
which we parse in link:run[] and then exit with the correct result ourselves... which we parse in link:run[] and then exit with the correct result ourselves...
Related thread: https://stackoverflow.com/questions/56032347/is-there-a-way-to-identify-if-gem5-run-got-over-successfully
==== gem5 syscall emulation mode program stdin ==== gem5 syscall emulation mode program stdin
gem5 shows its own stdout to terminal, and does not allow you to type stdin to programs. gem5 shows its own stdout to terminal, and does not allow you to type stdin to programs.
@@ -6005,7 +6007,9 @@ One possibility that gets close would be to use <<gdb>> to break at the `panic`
====== Exit gem5 on panic ====== Exit gem5 on panic
gem5 actually detects panics automatically by parsing kernel symbols and detecting when the PC reaches the address of the `panic` function. gem5 then prints to stdout: gem5 9048ef0ffbf21bedb803b785fb68f83e95c04db8 (January 2019) can detect panics automatically if the option `system.panic_on_panic` is on.
It parses kernel symbols and detecting when the PC reaches the address of the `panic` function. gem5 then prints to stdout:
.... ....
Kernel panic in simulated kernel Kernel panic in simulated kernel
@@ -6013,17 +6017,19 @@ Kernel panic in simulated kernel
and exits with status -6. and exits with status -6.
At gem5 ff52563a214c71fcd1e21e9f00ad839612032e3b (July 2018) behaviour was different, and just exited 0: https://www.mail-archive.com/gem5-users@gem5.org/msg15870.html TODO find fixing commit.
We enable the `system.panic_on_panic` option by default on `arm` and `aarch64`, which makes gem5 exit immediately in case of panic, which is awesome! We enable the `system.panic_on_panic` option by default on `arm` and `aarch64`, which makes gem5 exit immediately in case of panic, which is awesome!
If we don't set `system.panic_on_panic`, then gem5 just hangs. If we don't set `system.panic_on_panic`, then gem5 just hangs on an infinite guest loop.
TODO: why doesn't x86 support `system.panic_on_panic` as well? Trying to set `system.panic_on_panic` there fails with: TODO: why doesn't gem5 x86 ff52563a214c71fcd1e21e9f00ad839612032e3b support `system.panic_on_panic` as well? Trying to set `system.panic_on_panic` there fails with:
.... ....
AttributeError: Class LinuxX86System has no parameter panic_on_panic tried to set or access non-existentobject parameter: panic_on_panic
.... ....
However, as of f9eb0b72de9029ff16091a18de109c18a9ecc30a, panic on x86 makes gem5 crash with: However, at that commit panic on x86 makes gem5 crash with:
.... ....
panic: i8042 "System reset" command not implemented. panic: i8042 "System reset" command not implemented.
@@ -6040,6 +6046,8 @@ The implementation of panic detection happens at: https://github.com/gem5/gem5/b
Here we see that the symbol `"panic"` for the `panic()` function is the one being tracked. Here we see that the symbol `"panic"` for the `panic()` function is the one being tracked.
Related thread: https://stackoverflow.com/questions/56032347/is-there-a-way-to-identify-if-gem5-run-got-over-successfully
===== Reboot on panic ===== Reboot on panic
Make the kernel reboot after n seconds after panic: Make the kernel reboot after n seconds after panic: