Comment 3 for bug 1216845
Revision history for this message
| Peter Maydell (pmaydell) wrote Re: [Qemu-devel] [Bug 1216845] Re: qemu-system-arm semihosting always calls exit(0) | #3 |
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0e1f616
(Get the code!)
On 4 February 2015 at 15:56, Karl Zimmerman
<email address hidden> wrote:
> Had a similar problem with my emulation environment. However, I did
> some inspection of the assembly code generated by newlib for ARM semi-
> hosting. While it initially appears that exit() and _exit() discard the
> status code, upon careful inspection one finds that it is pushed on the
> stack, with the SP pointing right to it at the point at which the SWI is
> executed.
>
> Thus, if the code passed to 0x18 is 0x20026, you can fetch the status
> code passed to exit() from the stack.
Yes, but this is an internal implementation detail of newlib,
not a part of the semihosting ABI. It might well change
in different versions of newlib and we can't rely on it.
-- PMM