[PATCH v5 03/14] KVM: ARM: Initial skeleton to compile KVM support

Russell King - ARM Linux linux at arm.linux.org.uk
Wed Jan 16 04:44:44 EST 2013


On Wed, Jan 16, 2013 at 01:26:01PM +1030, Rusty Russell wrote:
> Christoffer Dall <c.dall at virtualopensystems.com> writes:
> 
> > On Mon, Jan 14, 2013 at 11:24 AM, Russell King - ARM Linux
> > <linux at arm.linux.org.uk> wrote:
> >> On Tue, Jan 08, 2013 at 01:38:55PM -0500, Christoffer Dall wrote:
> >>> +     /* -ENOENT for unknown features, -EINVAL for invalid combinations. */
> >>> +     for (i = 0; i < sizeof(init->features)*8; i++) {
> >>> +             if (init->features[i / 32] & (1 << (i % 32))) {
> >>
> >> Isn't this an open-coded version of test_bit() ?
> >
> > indeed, nicely spotted:
> 
> BTW, I wrote it that was out of excessive paranoia: it's a userspace
> API, and test_bit() won't be right on 64 bit BE systems.

So why is this a concern for 32-bit systems (which are, by definition,
only in arch/arm) ?



More information about the linux-arm-kernel mailing list