Bookmarks management

Key Mode Action
m+a Normal Show list of all bookmarks
m+m Normal Toggle bookmark in current line
m+n Normal Jump to next bookmark
m+p Normal Jump to previous bookmark
m+i Normal Annotate bookmark

As SpaceVim use above bookmarks mappings, so you can not use a, m, n, p or i registers to mark current position, but other registers should works will. if you really need to use these registers, you can add nnoremap <leader>m m to your custom configuration, then you use use a registers via \ma