Re: [Xen-devel] Frame buffer mmap not working in pvops dom0

[Eamon Walsh <ewalsh@xxxxxxxxxxxxx>]

On 07/21/2010 03:50 PM, Konrad Rzeszutek Wilk wrote:
>> The code path is fb_mmap with a NULL fbops->fb_mmap, so it just
>> delegates to the default code. Specifically, io_remap_pfn_range is where
>> the bad mapping is requested.
>>
>> I have a patch that fixes the issue, but I'm not sure under what
>> conditions the _PAGE_IOMAP bit needs to be set.
>>     
> Oh wow. That easy, eh?
>
>   
>> --- a/arch/x86/include/asm/fb.h
>> +++ b/arch/x86/include/asm/fb.h
>> @@ -10,6 +10,7 @@ static inline void fb_pgprotect
>>  {
>>         if (boot_cpu_data.x86 > 3)
>>                 pgprot_val(vma->vm_page_prot) |= _PAGE_PCD;
>> +       pgprot_val(vma->vm_page_prot) |= _PAGE_IOMAP;
>>  }
>>
>>  #ifdef CONFIG_X86_32
>>     
>
> I would say this patch is more sensible as the VM_IO flag had been
> set already, it just never got propagated:
>
>
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index 731fce6..187171b 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1362,6 +1362,7 @@ fb_mmap(struct file *file, struct vm_area_struct * vma)
>       vma->vm_pgoff = off >> PAGE_SHIFT;
>       /* This is an IO map - tell maydump to skip this VMA */
>       vma->vm_flags |= VM_IO | VM_RESERVED;
> +     vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
>       fb_pgprotect(file, vma, off);
>       if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
>                            vma->vm_end - vma->vm_start, vma->vm_page_prot))
>
>
> If that fixes your problem, are you OK with me sticking a Signed-off-by:
> from you on this patch?
>   


Either patch fixes the problem for me.

Tested-by: Eamon Walsh <ewalsh@xxxxxxxxxxxxx>



-- 

Eamon Walsh 
National Security Agency


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