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Date:   Sun, 16 Apr 2023 08:55:03 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Jason Adriaanse <jason_a69@yahoo.co.uk>
Cc:     robin.murphy@arm.com, baolu.lu@linux.intel.com, hch@lst.de,
        iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: [regression] Bug 217218 - Trying to boot Linux version 6-2.2
 kernel with Marvell SATA controller 88SE9235
Message-ID: <20230416065503.GB6410@lst.de>
References: <01c50370-002d-5e18-3edc-81c9527aedc9@arm.com> <04a94830-f626-2cd7-d220-7ba3025a409c@yahoo.co.uk>
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Hi Jason,

sorry for the late reply.  I had some email issues and am still
recovering from the backlog.

On Fri, Mar 31, 2023 at 10:20:37AM +0800, Jason Adriaanse wrote:
> Hi Christoph and Robin,
>
> Christoph - I would like to send you more dmesg information but as my boot 
> device cannot be detected that information is not being written to disk. Is 
> there any way to specifically write boot debug information to say a USB 
> device with some kernel parameters?

I don't know of any good way.  pstore has some ways to save kernel
messages, but it doesn't work to well with normal block devices in
case of crashes.

I'm a bit lost at the moment.

Two ideas I have, would be to

 1) boot with the intel_iommu=off kernel command line
 3) build a kernel with CONFIG_INTEL_IOMMU

and see if that works and report the dmesg.