[PVE-User] IOMMU and AMD-Vi useful/recommended for Proxmox ?

[Gilberto Nunes]

http://en.wikipedia.org/wiki/X86_virtualization#I.2FO_MMU_virtualization_.28AMD-Vi_and_VT-d.29


2014-08-21 13:06 GMT-03:00 <lst_hoe02 at kwsoft.de>:

> Hello,
>
> when inspecting the "dmesg" output on one of the PVE servers i got the
> follwoing:
>
> No AGP bridge found
> Node 0: aperture @ 0 size 32 MB
> Your BIOS doesn't leave a aperture memory hole
> Please enable the IOMMU option in the BIOS setup
> This costs you 64 MB of RAM
> Mapping aperture over 65536 KB of RAM @ 20000000
> PM: Registered nosave memory: 0000000020000000 - 0000000024000000
> AMD-Vi disabled by default: pass amd_iommu=on to enable
>
> My first action was to go to the BIOS (the machine is still test) and
> activated the IOMMU. The message stays the same. Next try was to set
> iommu=noaperture as boot parameter because it was suggested for machine
> having IOMMU but no AGP anymore. This lead to
>
> PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
> Placing 64MB software IO TLB between ffff880020000000 - ffff880024000000
> software IO TLB at phys 0x20000000 - 0x24000000
>
> Which looks like the IOMMU emulated in software...
>
> This lead to the question what the real benefits of AMD-Vi / IOMMU are for
> Proxmox/KVM if they are disabled by default and can not be enabled straight
> forward as it looks like?
>
> The Board in question is a ASUS KCMA-D8, BIOS 3102 with two AMD Opteron
> 4226 CPUs.
>
> Thanks for any hints
>
> Andreas
>
>
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>



-- 
Obrigado

Cordialmente

Gilberto Ferreira


Konnecta TI Tecnologia - Sistemas de Virtualização, Soluções de
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