From: David Vrabel <david.vrabel@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: Linux'es free_initmem() on Xen
Date: Tue, 2 Feb 2016 15:09:51 +0000 [thread overview]
Message-ID: <56B0C6BF.7000008@citrix.com> (raw)
In-Reply-To: <56B0C6FE02000078000CD88E@prv-mh.provo.novell.com>
On 02/02/16 14:10, Jan Beulich wrote:
>>>> On 02.02.16 at 14:30, <david.vrabel@citrix.com> wrote:
>> On 02/02/16 12:44, Jan Beulich wrote:
>>> All,
>>>
>>> while looking into some of the DEBUG_WX issues I came across
>>> aforementioned function and started wondering how pv-ops gets
>>> away without the unmapping XenoLinux has always been doing
>>> (in free_init_pages()).
>>
>> Um. I'm not sure why you think something needs to be unmapped. This is
>> freeing the pages back to the page allocator -- thus the pages still
>> need to be mapped.
>
> In the 1:1 mapping, yes. But the secondary mapping in the kernel
> VA range is not needed anymore, and (unless accounted for) would
> get in the way of said operations.
The PMDs are shared between the two mappings. See
xen_setup_kernel_pagetable().
David
next prev parent reply other threads:[~2016-02-02 15:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 12:44 Linux'es free_initmem() on Xen Jan Beulich
2016-02-02 13:30 ` David Vrabel
2016-02-02 14:10 ` Jan Beulich
2016-02-02 15:09 ` David Vrabel [this message]
2016-02-04 7:36 ` Jan Beulich
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