Re: [PATCH RESEND v2] x86: introduce ioremap_wc()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 17.02.2022 16:50, Roger Pau Monné wrote:
> On Thu, Feb 17, 2022 at 04:02:39PM +0100, Jan Beulich wrote:
>> On 17.02.2022 15:47, Roger Pau Monné wrote:
>>> On Thu, Feb 17, 2022 at 12:01:08PM +0100, Jan Beulich wrote:
>>>> --- a/xen/drivers/video/vga.c
>>>> +++ b/xen/drivers/video/vga.c
>>>> @@ -79,7 +79,7 @@ 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(0xB8000, 0x8000)) == NULL) )
>>>> +             ((video = ioremap_wc(0xB8000, 0x8000)) == NULL) )
>>>>              return;
>>>>          outw(0x200a, 0x3d4); /* disable cursor */
>>>>          columns = vga_console_info.u.text_mode_3.columns;
>>>> @@ -164,7 +164,11 @@ void __init video_endboot(void)
>>>>      {
>>>>      case XEN_VGATYPE_TEXT_MODE_3:
>>>>          if ( !vgacon_keep )
>>>> +        {
>>>>              memset(video, 0, columns * lines * 2);
>>>> +            iounmap(video);
>>>> +            video = ZERO_BLOCK_PTR;
>>>> +        }
>>>>          break;
>>>>      case XEN_VGATYPE_VESA_LFB:
>>>>      case XEN_VGATYPE_EFI_LFB:
>>>
>>> I think in vesa_endboot you also need to iounmap the framebuffer
>>> iomem?
>>
>> Again part of the full series. I guess I was a little inconsistent
>> with leaving the VGA unmap in here, but breaking out the VESA part.
>> It's been a long time, but I guess I did so because the VESA part
>> needs to touch two files.
> 
> I think you are hesitant to include the chunks for the above items? (or
> maybe I'm not properly accounting for their complexity).

There's no complexity, it's really just that the zapping of the pointer
needs to be done in a different place from where the unmap is. See below.

Jan

video/vesa: unmap frame buffer when relinquishing console

There's no point in keeping the VA space occupied when no further output
will occur.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- unstable.orig/xen/drivers/video/lfb.c
+++ unstable/xen/drivers/video/lfb.c
@@ -168,4 +168,5 @@ void lfb_free(void)
     xfree(lfb.lbuf);
     xfree(lfb.text_buf);
     xfree(lfb.line_len);
+    lfb.lfbp.lfb = ZERO_BLOCK_PTR;
 }
--- unstable.orig/xen/drivers/video/vesa.c
+++ unstable/xen/drivers/video/vesa.c
@@ -197,5 +197,7 @@ void __init vesa_endboot(bool_t keep)
                    vlfb_info.width * bpp);
         lfb_flush();
         lfb_free();
+        iounmap(lfb);
+        lfb = ZERO_BLOCK_PTR;
     }
 }