[Bug 1881249] Re: CPU fetch from unpopulated ROM on reset

[Philippe Mathieu-Daudé]

Different comments from Peter Maydell regarding this issue:

- https://www.mail-archive.com/qemu-devel@nongnu.org/msg683768.html

"We should be able to do this with the new 3-phase
reset API : the rom loader reset should happen in phase 2,
and the Arm CPU should only load the new PC and SP in
phase 3."

- https://www.mail-archive.com/qemu-devel@nongnu.org/msg686480.html

"The expectation at the moment is that the board code should
register a reset function with qemu_register_reset() which
calls cpu_reset(). Relying on doing a reset in realize won't
work for the case where there's a QEMU system reset, because
we don't re-init/realize everything, we just call all the
reset hooks.

If m68k reads pc/sp from memory on reset you'll probably run
into the same reset-ordering vs hw/cpu/loader.c that Arm M-profile
has; we currently work around that in the arm reset function."

- https://www.mail-archive.com/qemu-devel@nongnu.org/msg683856.html

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https://bugs.launchpad.net/bugs/1881249

Title:
  CPU fetch from unpopulated ROM on reset

Status in QEMU:
  New

Bug description:
  Some architectures fetch the $PC/$SP register as vectors in memory, usually 
ROM.
  The CPU reset() handler is called before the ROM code is populated, resulting 
in fetching incorrect PC/SP.

  Architectures affected:
  - M68K
  - RX
  - ARM M-profile

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