From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: Re: [PATCH] Use fixed-width types in the memory event
	interface
Date: Tue, 29 Jun 2010 15:52:35 +0100
Message-ID: <C84FC743.18FBC%keir.fraser@eu.citrix.com>
References: <AANLkTil6E4urMsFcMpDnommTNirSJ9SrGnBQJaIFFm19@mail.gmail.com>
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To: Patrick Colp <pjcolp@cs.ubc.ca>, Tim Deegan <Tim.Deegan@eu.citrix.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
List-Id: xen-devel@lists.xenproject.org

On 29/06/2010 15:37, "Patrick Colp" <pjcolp@cs.ubc.ca> wrote:

> A mostly unrelated question: I notice that vcpu_id is set to int32_t
> rather than uint32_t. This matches with the vcpu_id field in struct
> vcpu, but I'm just curious as to why this isn't an unsigned int in
> struct vcpu. Is there ever a time when vcpu_id is negative? I realise
> it's unlikely that we'll need to consider 4 billion vcpus (at least
> not anytime soon), but just wondering if there's any particular reason
> why this is a signed integer instead of an unsigned one.

No.

 K.

>=20
> Patrick
>=20
>=20
> On 29 June 2010 07:28, Patrick Colp <pjcolp@cs.ubc.ca> wrote:
>> On 29 June 2010 06:47, Tim Deegan <Tim.Deegan@citrix.com> wrote:
>>> Set the types in the public memory_event header file to use fixed-sized
>>> and self-aligned fields rather than "unsigned long". =A0AIUI this feature
>>> only works with 64-bit hypervisors but I think this change will be
>>> necessary to use 32-on-64 dom0 tools.
>>>=20
>>> This breaks compatibility with older builds of the tools, but I can't
>>> see any way to avoid it short of __attribute__((__packed__)).
>>>=20
>>> I'd like an ack/nack from Patrick on this, please.
>>>=20
>>> Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
>>=20
>> Acked-by: Patrick Colp <pjcolp@cs.ubc.ca>
>>=20
>>=20
>>=20
>>> diff -r 7b00193bd033 xen/include/public/mem_event.h
>>> --- a/xen/include/public/mem_event.h =A0 =A0Mon Jun 28 17:40:16 2010 +0100
>>> +++ b/xen/include/public/mem_event.h =A0 =A0Tue Jun 29 14:38:06 2010 +0100
>>> @@ -40,14 +40,14 @@
>>>=20
>>>=20
>>> =A0typedef struct mem_event_shared_page {
>>> - =A0 =A0int port;
>>> + =A0 =A0uint32_t port;
>>> =A0} mem_event_shared_page_t;
>>>=20
>>> =A0typedef struct mem_event_st {
>>> - =A0 =A0unsigned long gfn;
>>> - =A0 =A0unsigned long offset;
>>> - =A0 =A0unsigned long p2mt;
>>> - =A0 =A0int vcpu_id;
>>> + =A0 =A0uint64_t gfn;
>>> + =A0 =A0uint64_t offset;
>>> + =A0 =A0uint32_t p2mt;
>>> + =A0 =A0int32_t vcpu_id;
>>> =A0 =A0 uint64_t flags;
>>> =A0} mem_event_request_t, mem_event_response_t;
>>>=20
>>>=20
>>>=20
>>=20
>=20
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