From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@citrix.com>
Subject: Re: [PATCH v2 05/41] acpi : add helper function for
 mapping memory
Date: Wed, 20 May 2015 18:06:35 +0100
Message-ID: <555CBF1B.1030408@citrix.com>
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To: Jan Beulich <JBeulich@suse.com>, Parth Dixit <parth.dixit@linaro.org>
Cc: keir@xen.org, ian.campbell@citrix.com, andrew.cooper3@citrix.com, tim@xen.org, xen-devel@lists.xen.org, julien.grall@citrix.com, stefano.stabellini@citrix.com, christoffer.dall@linaro.org
List-Id: xen-devel@lists.xenproject.org

On 20/05/15 17:03, Jan Beulich wrote:
>>>> On 17.05.15 at 22:03, <parth.dixit@linaro.org> wrote:
>> --- a/xen/drivers/acpi/osl.c
>> +++ b/xen/drivers/acpi/osl.c
>> @@ -87,16 +87,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
>>  void __iomem *
>>  acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
>>  {
>> -	if (system_state >= SYS_STATE_active) {
>> -		unsigned long pfn = PFN_DOWN(phys);
>> -		unsigned int offs = phys & (PAGE_SIZE - 1);
>> -
>> -		/* The low first Mb is always mapped. */
>> -		if ( !((phys + size - 1) >> 20) )
>> -			return __va(phys);
>> -		return __vmap(&pfn, PFN_UP(offs + size), 1, 1, PAGE_HYPERVISOR_NOCACHE) + offs;
>> -	}
>> -	return __acpi_map_table(phys, size);
>> +    return acpi_os_map_iomem(phys, size);
>>  }
> 
> I think ioremap() (or maybe ioremap_cache()) should be used here,
> and tweaked suitably on x86 if need be.

ioremap_cache is most suitable for ARM.

ioremap (i.e ioremap_nocache) is mapping the region with device
attribute. Any unaligned access will result to a data abort.

Regards,

-- 
Julien Grall