Hi,
On 2/13/20 1:34 AM, Arvind Sankar wrote:
On Wed, Feb 12, 2020 at 04:57:19PM -0500, Arvind Sankar wrote:
However, I'm also getting confused about how mixed-mode works at all if
we have more than 4Gb RAM, which it seems we want to support as we take
pains to allocate a stack below 4Gb for the thunk. But in this case, the
kernel text and stack could be above 4Gb physically, so rather than
using a 1:1 map we'd need to find some space in the low 4Gb of virtual
addresses to map those, but I don't see where we do this? Also, that
dynamically allocated variable_name could be above 4G as well.
Verified in QEMU that mixed mode crashes if physical RAM can extend
above 4G. Are there any such real devices in existence? Should we check
that and disable runtime services if so?
AFAIK mixed-mode is mostly used on Bay Trail and maybe on one or 2 Cherry
Trail devices. Bay Trail does not go above 2G RAM and Cherry Trail does not
go above 4G RAM so in practice this should not be a problem.
I guess we could/should still document this somewhere ? Or maybe add a check
just for the sake of correctness?
Regards,
Hans
