[dpdk-dev] [PATCH] bus/fslmc: support for hotplugging of memory

[Shreyansh Jain]

> -----Original Message-----
> From: Burakov, Anatoly [mailto:anatoly.burakov at intel.com]
> Sent: Monday, April 9, 2018 9:20 PM
> To: Shreyansh Jain <shreyansh.jain at nxp.com>
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] bus/fslmc: support for hotplugging of
> memory
> 
> On 09-Apr-18 8:49 AM, Shreyansh Jain wrote:
> > Hello Anatoly,
> >
> > On Sunday 08 April 2018 10:44 PM, Burakov, Anatoly wrote:
> >> On 05-Apr-18 3:14 PM, Shreyansh Jain wrote:
> >>> Restructure VFIO DMA code for handling hotplug memory events
> >>> (callbacks) and --legacy case.
> >>>
> >>> Signed-off-by: Shreyansh Jain <shreyansh.jain at nxp.com>
> >>> ---
> >>>
> >>> ###
> >>> This is based on the 16fbfef04a3 github repository. This is assuming
> >>> that changes already exists as done in patch 26/68.
> >>> Though, this can be a standalone, replacing 26/88. Though, the
> Makefile
> >>> changes don't exist in this.
> >>> Also, this just a first draft. I will push any review changes after
> this
> >>> incrementally over v4.
> >>> ###
> >>
> >> Hi Shreyansh,
> >>
> >> I think we can keep the 26/68 as it still works within the context of
> >> the patchset. I would like to add these changes closer to the end,
> >> where we enable support for callbacks in VFIO (this could/should come
> >> as the next patch).
> >
> > But then it would also mean that dpaa2 would be broken within the
> memory
> > hotplug patches?
> > I think it would be broken once the memseg ceases to be continuous
> > physical sets.
> >
> 
> Hi Shreyansh,
> 
> Why would it be broken? Even when memseg change comes into effect,
> legacy mem is not enabled until much later in the patchset, when all of
> the callback/multiprocess business is in place. For all intents and
> purposes, this stays valid for legacy mode, hence not broken.

Ok. Then, I am mistaken. I was under the impression that as soon as memseg lists are introduced, when memseg stop being contiguous blocks, DPAA2 would have stopped working. I just didn't put an effort to check this.

> 
> We later enable callbacks etc. on VFIO, but technically they still
> aren't enabled until 65 (67 in v4), when it becomes possible to actually
> run DPDK in non-legacy mode.

Got it. Thanks.

> 
> So, for the duration of this patchset, dpaa2 is not broken, as far as i
> can tell. Keeping in mind that only legacy mode will be available until
> patch 65/67, what exactly is being broken here?
> 

Nothing, just a misunderstanding.

> --
> Thanks,
> Anatoly