Messages in this thread | | | Date | Sat, 4 Aug 2018 01:21:20 -0700 | From | Christoph Hellwig <> | Subject | Re: [RFC 0/4] Virtio uses DMA API for all devices |
| |
On Fri, Aug 03, 2018 at 01:58:46PM -0500, Benjamin Herrenschmidt wrote: > You are saying something along the lines of "I don't like an > instruction in your ISA, let's not support your entire CPU architecture > in Linux".
No. I'm saying if you can't describe your architecture in the virtio spec document it is bogus.
> Our setup is not fucked. It makes a LOT of sense and it's a very > sensible design. It's hitting a problem due to a corner case oddity in > virtio bypassing the MMU, we've worked around such corner cases many > times in the past without any problem, I fail to see what the problem > is here.
No matter if you like it or not (I don't!) virtio is defined to bypass dma translations, it is very clearly stated in the spec. It has some ill-defined bits to bypass it, so if you want the dma mapping API to be used you'll have to set that bit (in its original form, a refined form, or an entirely newly defined sane form) and make sure your hypersivors always sets it. It's not rocket science, just a little bit for work to make sure your setup is actually going to work reliably and portably.
> We aren't going to cancel years of HW and SW development for our
Maybe you should have actually read the specs you are claiming to implemented before spending all that effort.
| |