Hi Michał,
Thank you so much for reviewing.
On 11/7/22 5:26 PM, Michał Mirosław wrote:
+/*
- struct page_region - Page region with bitmap flags
- @start: Start of the region
- @len: Length of the region
- bitmap: Bits sets for the region
- */
+struct page_region {
__u64 start;__u64 len;__u32 bitmap;__u32 __reserved;"u64 flags"? If an extension is needed it would already require a new ioctl or something in the `arg` struct.
I feel like the masks must have the same type as this bitmap variable as the return_mask specifies the flags to be returned in bitmap. All the masks are of type __u32. This is why I'd kept the bitmap of type _u32 as well. I've kept them of 32 bit size as currently we are adding support for 4 flags and there is still room to add 28 more bits in the future. Do you still think that I should update the masks and bitmap to _u64?
- @start: Starting address of the region
- @len: Length of the region (All the pages in this length are included)
- @vec: Address of page_region struct array for output
- @vec_len: Length of the page_region struct array
- @max_pages: Optional max return pages (It must be less than vec_len if specified)
I think we discussed that this is not counting the same things as vec_len, so there should not be a reference between the two. The limit is whatever fits under both conditions (IOW: n_vecs <= vec_len && (!max_pages || n_pages <= max_pages).
In worse case when pages cannot be folded into the page_region, the one page_region may have information of only one page. This is why I've compared them. I want to communicate to the user that if max_pages is used, the vec_len should be of equal or greater size (to cater worse case which can happen at any time). Otherwise in worse case, the api can return without finding the max_pages number of pages. I don't know how should I put this in the comment.
(I only reviewed the API now. The implementation I think could be simpler, but let's leave that to after the API is agreed on.)
Best Regards Michał Mirosław