[PATCH v2 2/5] x86/vga: fix mapping of the VGA text buffer

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

The call to ioremap_wc() in video_init() will always fail, because
video_init() is called ahead of vm_init_type(), and so the underlying
__vmap() call will fail to allocate the linear address space.

Fix by reverting to the previous behavior and using ioremap() for the VGA
text buffer.

Fixes: 81d195c6c0e2 ('x86: introduce ioremap_wc()')
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v1:
 - No not attempt to adjust the directmap VGA text buffer mappings to be
   WC, just revert to the previous usage of UC- mappings for the whole VGA
   hole.
---
 xen/drivers/video/vga.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/video/vga.c b/xen/drivers/video/vga.c
index b4d018326128..ee6cf0a7079a 100644
--- a/xen/drivers/video/vga.c
+++ b/xen/drivers/video/vga.c
@@ -71,7 +71,7 @@ void __init video_init(void)
     {
     case XEN_VGATYPE_TEXT_MODE_3:
         if ( page_is_ram_type(paddr_to_pfn(0xB8000), RAM_TYPE_CONVENTIONAL) ||
-             ((video = ioremap_wc(0xB8000, 0x8000)) == NULL) )
+             ((video = ioremap(0xB8000, 0x8000)) == NULL) )
             return;
         outw(0x200a, 0x3d4); /* disable cursor */
         columns = vga_console_info.u.text_mode_3.columns;
@@ -158,7 +158,7 @@ void __init video_endboot(void)
         if ( !vgacon_keep )
         {
             memset(video, 0, columns * lines * 2);
-            iounmap(video);
+            /* No iounmap(), as it's a directmap mapping. */
             video = ZERO_BLOCK_PTR;
         }
         break;
-- 
2.48.1