From: Attilio Rao <attilio.rao@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
"Keir (Xen.org)" <keir@xen.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"Tim (Xen.org)" <tim@xen.org>,
Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
"allen.m.kay@intel.com" <allen.m.kay@intel.com>,
Jean Guyader <jean.guyader@eu.citrix.com>,
"Jean Guyader (3P)" <jean.guyader@citrix.com>
Subject: Re: Should we revert "mm: New XENMEM space, XENMAPSPACE_gmfn_range"?
Date: Thu, 2 Aug 2012 10:45:13 +0100 [thread overview]
Message-ID: <501A4C29.5080006@citrix.com> (raw)
In-Reply-To: <501A631D02000078000921B8@nat28.tlf.novell.com>
On 02/08/12 10:23, Jan Beulich wrote:
>>>> On 01.08.12 at 19:55, Stefano Stabellini<stefano.stabellini@eu.citrix.com> wrote:
>>>>
>> I was reading more about this commit because this patch breaks the ABI
>> on ARM, when I realized that on x86 there is no standard that specifies
>> the alignment of fields in a struct.
>>
> There is - the psABI supplements to the SVR4 ABI.
>
>
This is a completely different issue.
The problem here gcc/whatever compiler padding added to the struct in
order to have alignment of the members to the word boundry. The
difference is that this is not enforced in the ARM case (apparently,
from Stefano's report) while it happens in the x86 case.
This is why it is a good rule to organize member of a struct from the
bigger to the smaller when compiling with gcc and this is not the case
of the struct in question.
In the end it is a compiler decisional thing, not something decided by
the ABI.
Attilio
next prev parent reply other threads:[~2012-08-02 9:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-16 19:25 [PATCH 0/6] IOMMU, vtd and iotlb flush rework (v8) Jean Guyader
2011-11-16 19:25 ` [PATCH 1/6] vtd: Refactor iotlb flush code Jean Guyader
2011-11-16 19:25 ` [PATCH 2/6] iommu: Introduce iommu_flush and iommu_flush_all Jean Guyader
2011-11-16 19:25 ` [PATCH 3/6] add_to_physmap: Move the code for XENMEM_add_to_physmap Jean Guyader
2011-11-16 19:25 ` [PATCH 4/6] mm: New XENMEM space, XENMAPSPACE_gmfn_range Jean Guyader
2011-11-16 19:25 ` [PATCH 5/6] hvmloader: Change memory relocation loop when overlap with PCI hole Jean Guyader
2011-11-16 19:25 ` [PATCH 6/6] Introduce per cpu flag (iommu_dont_flush_iotlb) to avoid unnecessary iotlb flush Jean Guyader
2012-08-01 17:55 ` Should we revert "mm: New XENMEM space, XENMAPSPACE_gmfn_range"? Stefano Stabellini
2012-08-01 18:06 ` Keir Fraser
2012-08-02 9:25 ` Jan Beulich
2012-08-01 18:08 ` Tim Deegan
2012-08-02 9:23 ` Jan Beulich
2012-08-02 9:45 ` Attilio Rao [this message]
2012-08-02 10:22 ` Jan Beulich
2012-08-02 10:35 ` Attilio Rao
2012-08-02 12:57 ` Attilio Rao
2012-08-02 13:13 ` Stefano Stabellini
2012-08-02 13:36 ` Jan Beulich
2012-08-02 13:38 ` Stefano Stabellini
2011-11-19 21:58 ` [PATCH 3/6] add_to_physmap: Move the code for XENMEM_add_to_physmap Olaf Hering
2011-11-19 22:14 ` Keir Fraser
2011-11-19 22:37 ` Jean Guyader
2011-11-20 13:25 ` Olaf Hering
2011-11-20 19:59 ` Keir Fraser
2011-11-21 8:39 ` Olaf Hering
2011-11-17 9:20 ` [PATCH 0/6] IOMMU, vtd and iotlb flush rework (v8) Keir Fraser
2011-11-17 9:42 ` Jan Beulich
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