On Tue, Oct 24, 2017 at 01:32:51PM +0200, hpa@zytor.com wrote:

On October 17, 2017 5:42:41 PM GMT+02:00, "Kirill A. Shutemov" [off-list ref] wrote:

quoted

On Tue, Oct 03, 2017 at 11:27:54AM +0300, Kirill A. Shutemov wrote:

quoted

On Fri, Sep 29, 2017 at 05:08:15PM +0300, Kirill A. Shutemov wrote:

quoted

The first bunch of patches that prepare kernel to boot-time

switching

quoted

quoted

between paging modes.

Please review and consider applying.

Ping?

Ingo, is there anything I can do to get review easier for you?

I hoped to get boot-time switching code into v4.15...

One issue that has come up with this is what happens if the kernel is
loaded above 4 GB and we need to switch page table mode.  In that case
we need enough memory below the 4 GB point to hold a root page table
(since we can't write the upper half of cr3 outside of 64-bit mode) and
a handful of instructions.

We have no real way to know for sure what memory is safe without parsing
all the memory maps and map out all the data structures that The
bootloader has left for the kernel.  I'm thinking that the best way to
deal with this is to add an entry in setup_data to provide a pointers,
with the kernel header specifying a necessary size and alignment.

I would appreciate your feedback on my take on this:

http://lkml.kernel.org/r/20171020195934.32108-1-kirill.shutemov@linux.intel.com

I don't change boot protocol, but trying to guess the safe spot in the way
similar to what we do for realmode trampoline.

-- 
 Kirill A. Shutemov

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