Re: [PATCH v3 0/4] BaseIoFifoLib

[Jordan Justen <jordan.l.justen@intel.com>]

On 2017-01-09 08:37:38, Duran, Leo wrote:
> > -----Original Message-----
> > From: Laszlo Ersek [mailto:lersek@redhat.com]
> > Sent: Monday, January 09, 2017 9:14 AM
> > 
> > On 01/09/17 15:22, Duran, Leo wrote:
> > >
> > >> -----Original Message-----
> > >> From: Gao, Liming [mailto:liming.gao@intel.com]
> > >> Sent: Sunday, January 08, 2017 9:11 PM
> > >>
> > >> Leo:
> > >>   IoLib Library class is designed from the functionality, not code
> > >> implementation. So, many IO operations are included in this library
> > >> class. If developers want to use IO API, they only need to check IoLib
> > library class.
> > >> After add new APIs, we need to update all IoLib library instances to
> > >> implement them. And, if any library API implementation has the
> > >> different version, the full library instance will have to be copied
> > >> to another instance. I know your concern is to duplicate the library
> > >> implementation. But, I think this is the separate topic to optimize
> > >> the library implementation and reuse the same source file. Other
> > >> library instances may have the same issue. So, I suggest you submit
> > >> bugzilla for this optimization request. We will figure out the solution and
> > review it in this mail list.
> > >>
> > >
> > > I'm not sure I follow what you mean by an 'optimization request'.
> > 
> > I think under "optimization", Liming means eliminating code duplication
> > between IoLib library instances. That is, if I understand correctly, Liming and
> > Jordan suggest that you first add the new interfaces to the IoLib class header,
> > add (--> duplicate) the implementation to all library instances, then file a BZ
> > about eliminating code duplication between the library instances.
> > 
> > This is my understanding anyway.
> > 
> [Duran, Leo]  Thanks Lazlo... Unfortunately the 'ask' is still not clear to me.
> Liming,  I would appreciate some clarification.

Can you simplify the request down to what is needed, and not worry
about the 'IoFifoLib' implementation idea? Then put that into a
bugzilla feature request? I think that was Liming's request.

Would a reasonable example feature request be: "OVMF should detect
Secure Encrypted Virtualization mode, and if detected, it should not
use rep i/o instructions"

I think you should also try to provide details for how to detect SEV
mode in the feature request.

One situation that sounds familiar to me is
881813d7a93d9009c873515b043c41c4554779e4.

By the way, is this true? You simply cannot use those instructions?
It's not a matter of them being really slow, but they just don't work
at all?

-Jordan