Re: [Qemu-devel] [PATCH v7 1/3] sysbus: register reset handler for main_system_bus when created

[Eduardo Habkost]

On Tue, Jun 02, 2015 at 05:23:55PM +0800, Zhu Guihua wrote:
> Since icc bus will be droped and apic reset should be after bus
> reset in x86, this patch moves reset handler for main_system_bus
> from vl.c to sysbus.c

So, you are changing reset ordering for all machines because of a
x86-specific requirement?

Other machines can have different ordering requirements and may break if
you unconditionally change the reset order for all machines.

Like I said on v6: if x86 has specific CPU reset ordering requirements,
we should be able to ensure the expected ordering in x86-specific code
(in pc.c?), not hardcode reset ordering for all machines.

Maybe we can change the qemu_register_reset() API to accept an explicit
ordering parameter, so ordering requirements are visibly encoded in the
qemu_register_reset() calls instead of depending on non-obvious
initialization code ordering.

While we don't have a better API, we can probably ensure the x86 reset
ordering without affecting the other machines by calling
qemu_register_reset() for the CPUs in a machine_init_done notifier
registered by PC.

-- 
Eduardo