[dpdk-dev] [EXT] Re: [PATCH] bus/pci: fix IOVA as VA mode selection

[Burakov, Anatoly]

On 08-Jul-19 8:13 PM, Jerin Jacob Kollanukkaran wrote:
> See below,
> 
> Please send the email as text to avoid formatting issue.(No HTML)
> 
> From: David Marchand <david.marchand at redhat.com>
> Sent: Tuesday, July 9, 2019 12:09 AM
> To: Jerin Jacob Kollanukkaran <jerinj at marvell.com>
> Cc: dev <dev at dpdk.org>; Thomas Monjalon <thomas at monjalon.net>; Ben Walker <benjamin.walker at intel.com>; Burakov, Anatoly <anatoly.burakov at intel.com>
> Subject: [EXT] Re: [dpdk-dev] [PATCH] bus/pci: fix IOVA as VA mode selection
> 
> ________________________________________
> 
> On Mon, Jul 8, 2019 at 4:25 PM <mailto:jerinj at marvell.com> wrote:
> From: Jerin Jacob <mailto:jerinj at marvell.com>
> 
> Existing logic fails to select IOVA mode as VA
> if driver request to enable IOVA as VA.
> 
> IOVA as VA has more strict requirement than other modes,
> so enabling positive logic for IOVA as VA selection.
> 
> This patch also updates the default IOVA mode as PA
> for PCI devices as it has to deal with DMA engines unlike
> the virtual devices that may need only IOVA as DC.
> 
> We have three cases:
> - driver/hw supports IOVA as PA only
> 
> [Jerin] It is not driver cap, it is more of system cap(IOMMU vs non  IOMMU). We are already addressing that case

I don't get how this works. How does "system capability" affect what the 
device itself supports? Are we to assume that *all* hardware support 
IOVA as VA by default? "System capability" is more of a bus issue than 
an individual device issue, is it not?

-- 
Thanks,
Anatoly