Re: [patch 7/8] Add a bootparameter to reserve high linear address space.

Andrew Morton
2006-08-03T06:19:21Z

On Wed, 02 Aug 2006 17:25:17 -0700
Jeremy Fitzhardinge <jeremy@xensource.com> wrote:

> + /*
> + * reservetop=size reserves a hole at the top of the kernel
> + * address space which a hypervisor can load into later.
> + * Needed for dynamically loaded hypervisors, so relocating
> + * the fixmap can be done before paging initialization.
> + * This hole must be a multiple of 4M.
> + */
> + else if (!memcmp(from, "reservetop=", 11)) {
> + unsigned long reserve = memparse(from+11, &from);
> + reserve &= ~0x3fffff;
> + reserve_top_address(reserve);
> + }

I assume that this argument will normally be passed in via the hypervisor
rather than by human-entered information?

In which case, perhaps a panic would be a more appropriate response to a
non-multiple-of-4M.

Either way, rounding the number down rather than up seems wrong...