Re: [PATCH 2/2] virtio: change io privilege level as early as possible

[David Marchand <david.marchand@6wind.com>]

On Tue, Sep 29, 2015 at 9:25 PM, Stephen Hemminger <
stephen@networkplumber.org> wrote:

> On Tue, 10 Mar 2015 09:14:28 -0400
> Neil Horman <nhorman@tuxdriver.com> wrote:
>
> >
> > I don't see how this works for all cases.  The constructor is called
> once when
> > the library is first loaded.  What if you have multiple independent
> (i.e. not
> > forked children) processes that are using the dpdk in parallel?  Only the
> > process that triggered the library load will have io permissions set
> > appropriately.  I think what you need is to have every application that
> expects
> > to call through the transmit path or poll the receive path call iopl,
> which I
> > think speaks to having this requirement documented, so each application
> can call
> > iopl prior to calling fork/daemonize/etc.
> >
>
> I am still seeing this problem with DPDK 2.0 and 2.1.
> It seems to me that doing the iopl init in eal_init is the only safe way.
> Other workaround is to have application calling iopl_init before eal_init
> but that kind of violates the current method of all things being
> initialized
> by eal_init
>

Putting it in the virtio pmd constructor is my preferred solution and we
don't need to pollute the eal for virtio (specific to x86, btw).


-- 
David Marchand