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Re: [PATCH 2/2] hw/arm: remove exit(1) in case of missing ROM

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH 2/2] hw/arm: remove exit(1) in case of missing ROM
Date: Fri, 9 Oct 2020 18:00:31 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1

On 7/20/20 11:56 AM, Peter Maydell wrote:
On Wed, 15 Jul 2020 at 11:19, Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru> wrote:

This patch updates ARM-based machines to allow starting them without ROM.
In this case CPU starts to execute instructions from the empty memory,
but QEMU allows introspecting the machine configuration.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>

I guess this makes sense -- this is how most of our machines
already behave, so consistency and being able to introspect
the machine config are both worth having. Also these errors
mostly pre-date the 'generic loader' device, which is another
way to load guest code that the error-exit prevents. (You could
even load guest code via the gdbstub if you wanted...)

Note the 'generic loader' device allows you to select any CPU
address space, while gdbstub is restricted to the first CPU.

Calling arm_load_kernel() must not be conditional -- it is the
function which makes sure the guest CPU is reset.

(A handful of boards will call arm_load_kernel() only if
!qtest_enabled(), but most call it unconditionally. We should
look at why those handful of boards seem to need the conditional
and either remove it if useless or see if it should be applied
in other places or if arm_load_kernel() itself could be improved
to make the check unnecessary for all boards.)

Who should look at that? Maybe add that as a byte-sized task?



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