On 10/29/13 at 10:40am, Borislav Petkov wrote: > On Tue, Oct 29, 2013 at 02:47:20PM +0800, Dave Young wrote: > > Boris, could you update the comment? it says below: update that memory > > descriptor with the virtual address obtained from ioremap(). > > > > Logiclly your patch should update it, then my patch update it again > > with the case of mapping to fixed address for kexec. > > Thanks for catching this, I ended up doing the following: > > /* > * This function will switch the EFI runtime services to virtual mode. > * Essentially, we look through the EFI memmap and map every region that > * has the runtime attribute bit set in its memory descriptor into the > * ->trampoline_pgd page table using a top-down VA allocation scheme. > * > * The old method which used to update that memory descriptor with the > * virtual address obtained from ioremap() is still supported when the > * kernel is booted with efi=old_map on its command line. Same old > * method enabled the runtime services to be called without having to > * thunk back into physical mode for every invocation. > * > * The new method does a pagetable switch in a preemption-safe manner > * so that we're in a different address space when calling a runtime > * function. For function arguments passing we do copy the PGDs of the > * kernel page table into ->trampoline_pgd prior to each call. > */ Boris, thanks for update, it's very elaborate, I have still wonder if 32 bit case should be mentioned as well. Waiting for you next version of the patch series. I will redo my patches based on that. Thanks Dave -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
