From: Julien Grall <julien.grall@arm.com>
To: Vijay Kilari <vijay.kilari@gmail.com>
Cc: Tim Deegan <tim@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Jan Beulich <jbeulich@suse.com>,
Vijaya Kumar K <Vijaya.Kumar@cavium.com>
Subject: Re: [PATCH v4] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP
Date: Tue, 4 Apr 2017 09:00:13 +0100 [thread overview]
Message-ID: <7ed30365-3e26-823e-9ee8-d348d6ad93b9@arm.com> (raw)
In-Reply-To: <CALicx6tSfdWBLbZdqJQkRu+L1nBsUJogvdZMv5sDR7RSRe5Ung@mail.gmail.com>
On 04/04/2017 06:50 AM, Vijay Kilari wrote:
> Hi Julien,
Hello Vijay,
> On Mon, Apr 3, 2017 at 3:31 PM, Julien Grall <julien.grall@arm.com> wrote:
>> On 28/03/17 13:35, vijay.kilari@gmail.com wrote:
>>> diff --git a/xen/include/asm-arm/arm32/mm.h
>>> b/xen/include/asm-arm/arm32/mm.h
>>> new file mode 100644
>>> index 0000000..e93d9df
>>> --- /dev/null
>>> +++ b/xen/include/asm-arm/arm32/mm.h
>>> @@ -0,0 +1,20 @@
>>> +#ifndef __ARM_ARM32_MM_H__
>>> +#define __ARM_ARM32_MM_H__
>>> +
>>> +/* On ARM only xenheap memory is directly mapped. Hence return false. */
>>
>>
>> By reading this comment some people will wonder why you don't check whether
>> the mfn is in xenheap then. As mentioned above, I am ok if you always return
>> false here. But you need to explain why.
>
> Is this ok?
>
> "On ARM32, all the RAM is not mapped by Xen, instead it is mapped by xenheap.
> So DIRECTMAP_VIRT region is not mapped.
> Hence we return always false when mfn is checked on DIRECTMAP_VIRT region."
This does not make any sense. You don't map the RAM using xenheap,
xenheap is the only portion of the RAM always mapped. Furthermore, as I
said there are no "DIRECTMAP_VIRT" region on ARM, have a grep at this
keyword for ARM32...
How about:
"Only a limited amount of RAM, called xenheap, is always mapped on
ARM32. For convenience always return false."
Cheers,
--
Julien Grall
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prev parent reply other threads:[~2017-04-04 8:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-28 12:35 [PATCH v4] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP vijay.kilari
2017-03-28 12:51 ` Jan Beulich
2017-04-03 10:01 ` Julien Grall
2017-04-04 5:50 ` Vijay Kilari
2017-04-04 8:00 ` Julien Grall [this message]
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