From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
Subject: Re: [PATCH v3 0/3] force IOVA to a particular mode
Date: Tue, 30 Oct 2018 13:47:55 +0000
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Cc: eric.zhang@windriver.com, dev <dev@dpdk.org>,
 "Mcnamara, John" <john.mcnamara@intel.com>,
 Allain Legacy <allain.legacy@windriver.com>, matt.peters@windriver.com,
 Stephen Hemminger <stephen@networkplumber.org>,
 Ferruh Yigit <ferruh.yigit@intel.com>,
 Andrew Rybchenko <arybchenko@solarflare.com>,
 Maxime Coquelin <maxime.coquelin@redhat.com>,
 Shahaf Shuler <shahafs@mellanox.com>,
 Jerin Jacob <jerin.jacob@caviumnetworks.com>,
 Hemant Agrawal <hemant.agrawal@nxp.com>,
 David Marchand <david.marchand@6wind.com>
To: Alejandro Lucero <alejandro.lucero@netronome.com>,
 Thomas Monjalon <thomas@monjalon.net>
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On 30-Oct-18 12:02 PM, Alejandro Lucero wrote:
> 
> 
> On Sun, Oct 28, 2018 at 11:04 PM Thomas Monjalon <thomas@monjalon.net 
> <mailto:thomas@monjalon.net>> wrote:
> 
>     11/10/2018 12:08, Thomas Monjalon:
>      > +Cc more maintainers in order to collect more reviews
>      >
>      > 04/10/2018 11:19, Burakov, Anatoly:
>      > > On 03-Oct-18 9:53 PM, eric zhang wrote:
>      > > > This patchset introduces an EAL command line option "--iova-mode"
>      > > > to give the user a facility to force IOVA mode to a special
>     value.
>      > > >
>      > > > Auto detection of the IOVA mode, based on probing the bus and
>     IOMMU
>      > > > configuration, may not report the desired addressing mode
>     when virtual
>      > > > devices that are not directly attached to the bus are present.
>      > > > The EAL command line option "--iova-mode" can be used to
>     select either
>      > > > physical addressing('pa') or virtual addressing('va').
>      > >
>      > > Acked-by: Anatoly Burakov <anatoly.burakov@intel.com
>     <mailto:anatoly.burakov@intel.com>>
> 
>     Rebased and applied, thanks
> 
> 
> 
> Could not this lead to a problem if a device can not wok with the mode set?
> For example, IOVA mode set to VA and IOMMU hw with less bits than those 
> required for the virtual addresses?
> 
> IMO any device should be attached to a bus, and a bus should have a 
> function for setting IOVA mode and the --iova-mode option just allowed 
> with supported IOVA modes within the bus.

I don't think it should work that way. It should warn the user that an 
incompatible IOVA mode was selected, but the user has specified an IOVA 
mode for a reason - it probably implies he really means it, so let him :)

-- 
Thanks,
Anatoly