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Date:   Thu, 5 May 2022 11:07:47 -0300
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Subject: Re: Should arm64 have a custom crash shutdown handler?
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To:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc:     Marc Zyngier <maz@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        will Deacon <will@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Ard Biesheuvel <ardb@kernel.org>, broonie@kernel.org,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
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From:   "Guilherme G. Piccoli" <gpiccoli@igalia.com>
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On 05/05/2022 10:52, Vitaly Kuznetsov wrote:
> [...]
> For Hyper-V, the situation is similar: hv_crash_handler() intitiates
> VMbus unload on the crashing CPU only, there's no mechanism to do
> 'global' unload so other CPUs will likely not be able to connect Vmbus
> devices in kdump kernel but this should not be necessary.
> 
> There's a crash_kexec_post_notifiers mechanism which can be used instead
> but it's disabled by default so using machine_ops.crash_shutdown is
> better.
> 

Thanks a bunch Vitaly, for the clarification!

Just as a heads-up: there's been a panic notifiers refactor proposed [0]
in which some notifiers will run before kdump by default, not requiring
"crash_kexec_post_notifiers" (which BTW is *unfortunately* hardcoded as
'Y' for hyper-v, since a11589563e96).

Cheers,


Guilherme


[0]
https://lore.kernel.org/lkml/20220427224924.592546-1-gpiccoli@igalia.com/