On Tue, 04 May 2010 19:08:23 +0300 Avi Kivity <[email protected]> wrote:
> On 05/04/2010 06:03 PM, Arnd Bergmann wrote: > > On Tuesday 04 May 2010, Takuya Yoshikawa wrote: ... > >> So let us use the le bit offset calculation part by defining it as a new > >> macro: generic_le_bit_offset() . > >> > > Does this work correctly if your user space is 32 bits (i.e. unsigned long > > is different size in user space and kernel) in both big- and little-endian > > systems? > > > > I'm not sure about all the details, but I think you cannot in general share > > bitmaps between user space and kernel because of this. > > > > That's why the bitmaps are defined as little endian u64 aligned, even on > big endian 32-bit systems. Little endian bitmaps are wordsize agnostic, > and u64 alignment ensures we can use long-sized bitops on mixed size > systems. There was a suggestion to propose set_le_bit_user() kind of macros. But what I thought was these have a constraint you two explained and seemed to be a little bit specific to some area, like KVM. So I decided to propose just the offset calculation macro. Thanks, Takuya -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
