Linux IOMMU Development
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From: Valentine Sinitsyn <valentine.sinitsyn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: David Kiarie
	<davidkiarie4-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: IVDB DTE_ALL Settings
Date: Wed, 05 Aug 2015 14:53:14 +0500	[thread overview]
Message-ID: <55C1DD0A.4060601@gmail.com> (raw)
In-Reply-To: <20150805094836.GR14980-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>

Hi Joerg,

On 05.08.2015 14:48, Joerg Roedel wrote:
> On Tue, Aug 04, 2015 at 10:05:45PM +0500, Valentine Sinitsyn wrote:
>> Not directly related to the issue David discovered, but as we
>> discuss IVRS handling: the specification says that ACPI tables data
>> overrides what's in hardware registers (Sect. 5). To the best of my
>> understanding, this means e.g. I should take HATS value not from EFR
>> but from IVHD Type 10 block. However, amd_iommu driver code checks
>> for features directly - for what reason? I'm not suggesting this is
>> a bug, but rather asking your opinion here.
>
> In my experience the hardware is more trustable than the ACPI table. We
> had several issues with broken BIOSes that screw up the IVRS ACPI table,
> so my trust in the values there is limited.
Makes sense. Thank you for sharing.

Valentine

      parent reply	other threads:[~2015-08-05  9:53 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-04  2:57 IVDB DTE_ALL Settings David Kiarie
     [not found] ` <20150804025745.GA4128-FBVcP3zgNXf1IFe7KZLm3A@public.gmane.org>
2015-08-04 16:56   ` Joerg Roedel
     [not found]     ` <20150804165619.GP14980-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-08-04 17:05       ` Valentine Sinitsyn
     [not found]         ` <55C0F0E9.6030902-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-08-05  9:48           ` Joerg Roedel
     [not found]             ` <20150805094836.GR14980-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-08-05  9:53               ` Valentine Sinitsyn [this message]

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