On Tue, Oct 24, 2017 at 01:32:51PM +0200, hpa@xxxxxxxxx wrote: > On October 17, 2017 5:42:41 PM GMT+02:00, "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote: > >On Tue, Oct 03, 2017 at 11:27:54AM +0300, Kirill A. Shutemov wrote: > >> On Fri, Sep 29, 2017 at 05:08:15PM +0300, Kirill A. Shutemov wrote: > >> > The first bunch of patches that prepare kernel to boot-time > >switching > >> > 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@xxxxxxxxxxxxxxx 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
