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Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW fun
From: |
Benjamin Herrenschmidt |
Subject: |
Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function |
Date: |
Mon, 21 May 2012 07:36:08 +1000 |
On Sat, 2012-05-19 at 09:24 +0200, Paolo Bonzini wrote:
> I guess the C11/C++ guys required an isync barrier after either loads or
> stores, because they need to order the load/store vs. code accessing
> other memory. This is not needed in QEMU because all guest accesses go
> through cpu_physical_memory_rw (or has its own barriers).
I am not sure, I don't quite see what it buys them really. I'd have to
ask Paul McKenney, he probably knows :-)
Cheers,
Ben.
- Re: [Qemu-devel] [RFC/PATCH] Add a memory barrier to guest memory access functions, (continued)
- Re: [Qemu-devel] [RFC/PATCH] Add a memory barrier to guest memory access functions, David Gibson, 2012/05/16
- Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function, Paolo Bonzini, 2012/05/18
- Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function, Benjamin Herrenschmidt, 2012/05/18
- Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function, Paolo Bonzini, 2012/05/18
- Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function, Benjamin Herrenschmidt, 2012/05/18
- Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function, Paolo Bonzini, 2012/05/19
- Re: [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function,
Benjamin Herrenschmidt <=
- [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Benjamin Herrenschmidt, 2012/05/20
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Paolo Bonzini, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Michael S. Tsirkin, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Benjamin Herrenschmidt, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Benjamin Herrenschmidt, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Benjamin Herrenschmidt, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Michael S. Tsirkin, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Benjamin Herrenschmidt, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Michael S. Tsirkin, 2012/05/21
- Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions, Benjamin Herrenschmidt, 2012/05/21