On Wed, Feb 24, 2016 at 10:19 AM, Boris Ostrovsky
wrote:
> Baremetal kernels clear .bss early in the boot but Xen PV guests don't
> execute that code. They have been able to run without problems because
> Xen domain builder happens to give out zeroed pages. However, since this
> is not really guar
On 02/24/2016 12:26 PM, Andrew Cooper wrote:
On 24/02/16 15:19, Boris Ostrovsky wrote:
+ /* Clear .bss */
+ xor REG(ax),REG(ax)
If we are nitpicking,
This should be xor %eax, %eax even in 64bit. Functionally identical,
and shorter to encode.
Right, Brian Gerst pointed this out t
On 24/02/16 15:19, Boris Ostrovsky wrote:
> Baremetal kernels clear .bss early in the boot but Xen PV guests don't
> execute that code. They have been able to run without problems because
> Xen domain builder happens to give out zeroed pages. However, since this
> is not really guaranteed, .bss sho
On 02/24/2016 11:05 AM, Brian Gerst wrote:
Use the macros in instead of defining your own. Also,
xorl %eax,%eax is good for 64-bit too, since the upper bits are
cleared.
I suspected this would have to be defined somewhere but couldn't find
it. Thanks!
-boris
Baremetal kernels clear .bss early in the boot but Xen PV guests don't
execute that code. They have been able to run without problems because
Xen domain builder happens to give out zeroed pages. However, since this
is not really guaranteed, .bss should be explicitly cleared.
(Since we introduce ma
