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From: Robin Murphy <robin.murphy@arm.com>
To: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>,
	Oleksandr Tyshchenko <olekstysh@gmail.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v3 1/2] dt-bindings: arm: xen: document Xen iommu device
Date: Wed, 26 Jan 2022 15:54:25 +0000	[thread overview]
Message-ID: <447f89ca-86c0-dc35-e7ac-e6639a573670@arm.com> (raw)
In-Reply-To: <PAXPR03MB81144A63E18CAF10E785E2A7F0209@PAXPR03MB8114.eurprd03.prod.outlook.com>

On 2022-01-26 15:09, Sergiy Kibrik wrote:
> Hi Robin,
> 
>>
>> This could break Linux guests, since depending on the deferred probe
>> timeout setting it could lead to drivers never probing because the "IOMMU"
>> never becomes available.
>>
> 
> I've noticed no deferred probe timeouts when booting with this patch. Could you please explain more on how this would break guests?

Right now I think it would actually require command-line intervention, 
e.g. "fw_devlink=on" or "deferred_probe_timeout=3600" (with modules 
enabled for the latter to take full effect), but I'm wary of the 
potential for future config options to control those behaviours by default.

Robin.

> Thank you!
> 
>   -- Sergiy


WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com>
To: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>,
	Oleksandr Tyshchenko <olekstysh@gmail.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v3 1/2] dt-bindings: arm: xen: document Xen iommu device
Date: Wed, 26 Jan 2022 15:54:25 +0000	[thread overview]
Message-ID: <447f89ca-86c0-dc35-e7ac-e6639a573670@arm.com> (raw)
In-Reply-To: <PAXPR03MB81144A63E18CAF10E785E2A7F0209@PAXPR03MB8114.eurprd03.prod.outlook.com>

On 2022-01-26 15:09, Sergiy Kibrik wrote:
> Hi Robin,
> 
>>
>> This could break Linux guests, since depending on the deferred probe
>> timeout setting it could lead to drivers never probing because the "IOMMU"
>> never becomes available.
>>
> 
> I've noticed no deferred probe timeouts when booting with this patch. Could you please explain more on how this would break guests?

Right now I think it would actually require command-line intervention, 
e.g. "fw_devlink=on" or "deferred_probe_timeout=3600" (with modules 
enabled for the latter to take full effect), but I'm wary of the 
potential for future config options to control those behaviours by default.

Robin.

> Thank you!
> 
>   -- Sergiy

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2022-01-26 15:54 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-17 12:32 [PATCH v3 0/2] Avoid using Xen DMA ops when the device is protected by an IOMMU Sergiy Kibrik
2022-01-17 12:32 ` Sergiy Kibrik
2022-01-17 12:32 ` [PATCH v3 1/2] dt-bindings: arm: xen: document Xen iommu device Sergiy Kibrik
2022-01-17 12:32   ` Sergiy Kibrik
2022-01-17 15:30   ` Robin Murphy
2022-01-17 15:30     ` Robin Murphy
2022-01-18 22:32     ` Stefano Stabellini
2022-01-18 22:32       ` Stefano Stabellini
2022-01-26 15:09     ` Sergiy Kibrik
2022-01-26 15:09       ` Sergiy Kibrik
2022-01-26 15:54       ` Robin Murphy [this message]
2022-01-26 15:54         ` Robin Murphy
2022-01-26 18:56         ` Stefano Stabellini
2022-01-26 18:56           ` Stefano Stabellini
2022-02-05  2:14           ` Rob Herring
2022-02-05  2:14             ` Rob Herring
2022-02-08  0:53             ` Stefano Stabellini
2022-02-08  0:53               ` Stefano Stabellini
2023-05-04  9:33               ` Oleksii Moisieiev
2023-05-04  9:33                 ` Oleksii Moisieiev
2022-01-17 12:32 ` [PATCH v3 2/2] arm/xen: don't use xen DMA ops when the device is protected by an IOMMU Sergiy Kibrik
2022-01-17 12:32   ` Sergiy Kibrik

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