From: Nicolin Chen nicolinc@nvidia.com Sent: Tuesday, November 21, 2023 1:37 AM
On Mon, Nov 20, 2023 at 08:34:58AM +0000, Tian, Kevin wrote:
From: Liu, Yi L yi.l.liu@intel.com Sent: Monday, November 20, 2023 4:30 PM
On 2023/11/20 16:09, Tian, Kevin wrote:
From: Liu, Yi L yi.l.liu@intel.com Sent: Friday, November 17, 2023 9:07 PM
- @req_len: Length (in bytes) of a request entry in the request array
- @req_num: Input the number of cache invalidation requests in the
array.
Output the number of requests successfully handled bykernel.
- @out_driver_error_code: Report a driver speicifc error code upon
failure.
It's optional, driver has a choice to fill it or
not.Being optional how does the user tell whether the code is filled or not?
Well, naming it "error_code" indicates zero means no error while non-zero means something? An error return from this ioctl could also tell the user space to look up for this driver error code, if it ever cares.
probably over-thinking but I'm not sure whether zero is guaranteed to mean no error in all implementations...
seems like we need a flag for it. otherwise, a reserved special value is required. or is it enough to just document it that this field is available or not per the iommu_hw_info_type?
No guarantee that a reserved special value applies to all vendors.
I'll just remove the optional part. the viommu driver knows what a valid code is, if the driver fills it.
Hmm, remove out_driver_error_code? Do you mean by reusing ioctl error code to tell the user space what driver error code it gets?
No. I just meant to remove the last sentence "It's optional ..."