From: Avi Kivity <avi@qumranet.com>
To: Chris Wright <chrisw@sous-sol.org>
Cc: Izik Eidus <izike@qumranet.com>,
andrea@qumranet.com, yaniv@qumranet.com,
kvm-devel <kvm-devel@lists.sourceforge.net>,
linux-mm@kvack.org
Subject: Re: [kvm-devel] [RFC][PATCH 3/5] ksm source code
Date: Thu, 24 Jan 2008 21:41:06 +0200 [thread overview]
Message-ID: <4798E9D2.8030503@qumranet.com> (raw)
In-Reply-To: <20080124175132.GR3627@sequoia.sous-sol.org>
Chris Wright wrote:
>>> struct ksm_memory_region {
>>> __u32 npages; /* number of pages to share */
>>> __u64 addr; /* the begining of the virtual address */
>>> };
>>>
>> why isnt it compat safe?
>>
>
> 32-bit has more relaxed alignment requirement for __u64 (4 bytes)
> than 64-bit (8 bytes). choices are reverse the order or add padding
> (can test by compiling structure in 32 and 64 bit).
>
Reversing the order isn't good enough, since the structure size would be
different, and that is embedded in the ioctl number. Padding is necessary.
[wishlist: struct { ... } __attribute__((abi_x86_64));]
--
Any sufficiently difficult bug is indistinguishable from a feature.
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next prev parent reply other threads:[~2008-01-24 19:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-21 16:12 Izik Eidus
2008-01-24 7:24 ` [kvm-devel] " Chris Wright
2008-01-24 9:07 ` Izik Eidus
2008-01-24 9:22 ` Avi Kivity
2008-01-24 9:48 ` Izik Eidus
2008-01-24 17:53 ` Chris Wright
2008-01-24 17:51 ` Chris Wright
2008-01-24 19:41 ` Avi Kivity [this message]
2008-01-24 20:34 ` Chris Wright
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