From:   Niklas Cassel <Niklas.Cassel@wdc.com>
To:     John Garry <john.garry@huawei.com>
CC:     "Ajish.Koshy@microchip.com" <Ajish.Koshy@microchip.com>,
        "jinpu.wang@cloud.ionos.com" <jinpu.wang@cloud.ionos.com>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "Viswas.G@microchip.com" <Viswas.G@microchip.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>
Subject: Re: [PATCH] scsi: pm8001: Fix phys_to_virt() usage on dma_addr_t
Thread-Topic: [PATCH] scsi: pm8001: Fix phys_to_virt() usage on dma_addr_t
Thread-Index: AQHX6qST8eOxJfqT20yZh1HFV7vkWA==
Date:   Mon, 6 Dec 2021 13:24:19 +0000
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On Mon, Dec 06, 2021 at 09:42:23AM +0000, John Garry wrote:
> On 29/11/2021 10:46, Ajish.Koshy@microchip.com wrote:
> > Thanks John for the update. Based on the given issue,
> > we never tested on arm server.
> >=20
> > Further arm testing will depend on the availability of
> > the server.
> >=20
> > Meanwhile will do further test on x86 and update
> > on the observations.
>=20
> Have you tested on x86 with the IOMMU enabled? From my limited experience=
,
> out of the box the IOMMU is disabled in the BIOS on x86 machines - that i=
s a
> very general statement. But this is not just an issue specific to arm64.

My limited experience tells me the opposite, that modern x64 servers
have IOMMU enabled by default:

E.g.:
https://www.dell.com/support/manuals/en-uk/poweredge-r7515/r7515_bios_pub/p=
rocessor-settings?guid=3Dguid-ec36d324-4f45-4bc1-bb51-de2db7cc5cd9&lang=3De=
n-us
https://support.hpe.com/hpesc/public/docDisplay?docId=3Da00025662en_us&docL=
ocale=3Den_US


This driver not working properly on a system with an IOMMU just tells
us that the number of mainline users of this driver is very low :/


Kind regards,
Niklas=