Re: [PATCH 09/10] hw/core/machine: Use qemu_register_resettable for sysbus reset

[Zhao Liu]

On Tue, Feb 20, 2024 at 04:06:21PM +0000, Peter Maydell wrote:
> Date: Tue, 20 Feb 2024 16:06:21 +0000
> From: Peter Maydell <peter.maydell@linaro.org>
> Subject: [PATCH 09/10] hw/core/machine: Use qemu_register_resettable for
>  sysbus reset
> X-Mailer: git-send-email 2.34.1
> 
> Move the reset of the sysbus (and thus all devices and buses anywhere
> on the qbus tree) from qemu_register_reset() to qemu_register_resettable().
> 
> This is a behaviour change: because qemu_register_resettable() is
> aware of three-phase reset, this now means that:
>  * 'enter' phase reset methods of devices and buses are called
>    before any legacy reset callbacks registered with qemu_register_reset()
>  * 'exit' phase reset methods of devices and buses are called
>    after any legacy qemu_register_reset() callbacks
> 
> Put another way, a qemu_register_reset() callback is now correctly
> ordered in the 'hold' phase along with any other 'hold' phase methods.
> 
> The motivation for doing this is that we will now be able to resolve
> some reset-ordering issues using the three-phase mechanism, because
> the 'exit' phase is always after the 'hold' phase, even when the
> 'hold' phase function was registered with qemu_register_reset().
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I believe that given we don't make much use of enter/exit phases
> currently that this is unlikely to cause unexpected regressions due
> to an accidental reset-order dependency that is no longer satisfied,
> but it's always possible...
> ---
>  hw/core/machine.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>