Messages in this thread | | | Date | Wed, 16 Feb 2022 15:11:15 +0800 | Subject | Re: [PATCH v2 09/11] iommu/vt-d: Remove commented code | From | Lu Baolu <> |
| |
On 2/16/22 11:45 AM, Tian, Kevin wrote: >> From: Christoph Hellwig<hch@lst.de> >> Sent: Monday, February 14, 2022 3:34 PM >> >> On Mon, Feb 14, 2022 at 10:57:02AM +0800, Lu Baolu wrote: >>> This removes unnecessary commented code. >> Removing dead code is always good: >> >> Reviewed-by: Christoph Hellwig<hch@lst.de> >> >> But someone might really want to take a look if draining makes sense here >> or not. > Looks that dead code has been there since intel-iommu driver was > firstly introduced in 2007. I don't know whether we can dig out > the reason (Baolu, can you have a check?) why it's only special > cased for read draining but not write draining. I cannot find any > such recommendation from VT-d spec.
Emm, I have no idea either. Let me check it with the architecture experts.
> > Looking at VT-d spec it stated that since VT-d major version 2 > drain is conducted automatically by hardware and above flags > are essentially ignored. > > Given that possibly a safer option is to always set read/write > draining flags before version 2 and skip it after.
Best regards, baolu
| |