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From: Joerg Roedel <>
To: Qian Cai <>
Cc:, Joerg Roedel <>,
Subject: Re: [PATCH v2 0/2] iommu/amd: Don't use atomic64_t for domain->pt_root
Date: Tue, 30 Jun 2020 11:57:21 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, Jun 26, 2020 at 08:30:21AM -0400, Qian Cai wrote:
> BTW, from the previous discussion, Linus mentioned,
> “
> The thing is, the 64-bit atomic reads/writes are very expensive on
> 32-bit x86. If it was just a native pointer, it would be much cheaper
> than an "atomic64_t".
> “
> However, here we have AMD_IOMMU depend on x86_64, so I am wondering if
> it makes any sense to run this code on 32-bit x86 at all?

No, it doesn't, the driver is not supported on 32bit and probably never
will. I skip this patch and only apply the first one, as it is an
improvement in itself.


iommu mailing list

      reply	other threads:[~2020-06-30  9:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-26  8:05 [PATCH v2 0/2] iommu/amd: Don't use atomic64_t for domain->pt_root Joerg Roedel
2020-06-26  8:05 ` [PATCH v2 1/2] iommu/amd: Add helper functions to update domain->pt_root Joerg Roedel
2020-06-26  8:05 ` [PATCH v2 2/2] iommu/amd: Use 'unsigned long' for domain->pt_root Joerg Roedel
2020-06-26 12:30 ` [PATCH v2 0/2] iommu/amd: Don't use atomic64_t " Qian Cai
2020-06-30  9:57   ` Joerg Roedel [this message]

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