Hi loody, On Mon, Nov 7, 2011 at 5:16 AM, loody <miloody@gmail.com> wrote: ...snip...
1. Are all struct page 32-bit aligned?
Certainly, I would expect any structures found in the system memory map to be so aligned, yes. If you've created an arbitrary one elsewhere I'm only 99% sure it would be.
If so, where is this part of code for handleing struct page be 32-bits aligned?
Note that the size of struct page is carefully considered, and that they are packed as densely as possible, both externally and internally. No lesser alignment would make sense. I found kernel stealing LSB of page_link to put additional information, such as sg_is_chain and sg_is_last.
That means the address of all pages have to be at least 4byte alignment. But I didn't see any additional attribute added at the end of struct or any precaution to take care this.
This is done automatically by the compiler. http://en.wikipedia.org/wiki/Data_structure_alignment -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com