Hi loody,

On Mon, Nov 7, 2011 at 5:16 AM, loody [off-list ref] wrote:
...snip...

quoted

quoted

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.

quoted

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