Re: [PATCH v3 1/3] x86/ioreq server(patch for 4.7): Rename p2m_mmio_write_dm to p2m_ioreq_server.

From: "Jan Beulich" <JBeulich@suse.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>,
	Yu Zhang <yu.c.zhang@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Wei Liu <wei.liu2@citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Tim Deegan <tim@xen.org>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	Paul Durrant <paul.durrant@citrix.com>,
	Zhiyuan Lv <zhiyuan.lv@intel.com>,
	Jun Nakajima <jun.nakajima@intel.com>, Keir Fraser <keir@xen.org>
Subject: Re: [PATCH v3 1/3] x86/ioreq server(patch for 4.7): Rename p2m_mmio_write_dm to p2m_ioreq_server.
Date: Mon, 25 Apr 2016 08:14:11 -0600	[thread overview]
Message-ID: <571E425302000078000E5621@prv-mh.provo.novell.com> (raw)
In-Reply-To: <CAFLBxZavhPdTmxjR-prgiJY9VALjQg10KjqpAn3N5mhuC+XpmQ@mail.gmail.com>

>>> On 25.04.16 at 15:39, <George.Dunlap@eu.citrix.com> wrote:
> On Mon, Apr 25, 2016 at 11:35 AM, Yu Zhang <yu.c.zhang@linux.intel.com> wrote:
>> --- a/xen/include/public/hvm/hvm_op.h
>> +++ b/xen/include/public/hvm/hvm_op.h
>> @@ -83,7 +83,13 @@ typedef enum {
>>      HVMMEM_ram_rw,             /* Normal read/write guest RAM */
>>      HVMMEM_ram_ro,             /* Read-only; writes are discarded */
>>      HVMMEM_mmio_dm,            /* Reads and write go to the device model */
>> -    HVMMEM_mmio_write_dm       /* Read-only; writes go to the device model */
>> +#if __XEN_INTERFACE_VERSION__ < 0x00040700
>> +    HVMMEM_mmio_write_dm,      /* Read-only; writes go to the device model */
>> +#else
>> +    HVMMEM_unused,             /* Placeholder; setting memory to this type
>> +                                  will fail for code after 4.7.0 */
>> +#endif
>> +    HVMMEM_ioreq_server
> 
> Also, I don't think we've had a convincing argument for why this patch
> needs to be in 4.7.  The p2m name changes are internal only, and so
> don't need to be made at all; and the old functionality will work as
> well as it ever did.  Furthermore, the whole reason we're in this
> situation is that we checked in a publicly-visible change to the
> interface before it was properly ready; I think we should avoid making
> the same mistake this time.

Good point.

> So personally I'd just leave this patch entirely for 4.8; but if Paul
> and/or Jan have strong opinions, then I would say check in only a
> patch to do the #if/#else/#endif, and leave both the p2m type changes
> and the new HVMMEM_ioreq_server enum for when the 4.8 development
> window opens.

Doing that alone would break the build - it would need to be a
little more than that.

Jan

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