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Subject: Re: Patches for stable
To: Greg KH <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        xen-devel <xen-devel@lists.xenproject.org>
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 <20180404142702.GA20460@kroah.com>
From: Juergen Gross <jgross@suse.com>
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Date: Wed, 4 Apr 2018 16:30:30 +0200
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On 04/04/18 16:27, Greg KH wrote:
> On Wed, Apr 04, 2018 at 12:38:43PM +0200, Juergen Gross wrote:
>> Please add the patches:
>>
>> commit 038bac2b02989acf1fc938cedcb7944c02672b9f upstream
>> commit dfc9327ab7c99bc13e12106448615efba833886b upstream
>> commit b17d9d1df3c33a4f1d2bf397e2257aecf9dc56d4 upstream
>>
>> to the 4.15 and 4.16 stable kernels.
>>
>> Those patches are needed to boot Linux as PVH guest on recent Xen.
> 
> So a new feature?  Why is that ok for stable kernels?

It works for kernels since at least 4.11 on Xen 4.10.

> 
>> In PVH mode there is no guarantee the kernel can find the RSDP table
>> at the legacy location in low memory, which is a requirement for the
>> kernel to boot successful without those patches.
> 
> Why not just use newer kernels for new Xen features?  This really
> doesn't look like a bugfix to me, does it to you?

It does. A working setup will no longer work if Xen version is upgraded
to 4.11.


Juergen