MFC r286808, r286809, r286867, r286868

-   Improve support for Macs that have a stride not equal to the
    horizonal resolution (width).
-   Support frame buffers that are larger than the default screen
    size.
-   Support large frame buffers: add 24 more page table pages we
    allocate on boot-up.

PR:		193745

1 files changed, 7 insertions, 1 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 074388b..b47e97c 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -701,8 +701,14 @@ nkpt_init(vm_paddr_t addr)
 	 * pmap_growkernel() will need to allocate page table pages to map
 	 * the entire 512GB of KVA space which is an unnecessary tax on
 	 * physical memory.
+	 *
+	 * Secondly, device memory mapped as part of setting up the low-
+	 * level console(s) is taken from KVA, starting at virtual_avail.
+	 * This is because cninit() is called after pmap_bootstrap() but
+	 * before vm_init() and pmap_init(). 20MB for a frame buffer is
+	 * not uncommon.
 	 */
-	pt_pages += 8;		/* 16MB additional slop for kernel modules */
+	pt_pages += 32;		/* 64MB additional slop. */
 #endif
 	nkpt = pt_pages;
 }