From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: "Skidanov, Alexey" <Alexey.Skidanov@amd.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: 32 bit user space compatibility
Date: Tue, 28 Oct 2014 22:34:35 +0000 [thread overview]
Message-ID: <20141028223435.73b3778c@alan.etchedpixels.co.uk> (raw)
In-Reply-To: <AD975D71AAD7784D8D1265DF6444C2FD0C4307FC@storexdag03.amd.com>
On Sun, 26 Oct 2014 12:25:08 +0000
"Skidanov, Alexey" <Alexey.Skidanov@amd.com> wrote:
> Hi,
>
> Running 32 bit user space needs some work to be done with ioctls. I understand that there are two options to implement:
> 1. Use only fixed size types. Pad IOCTLS params to multiple of 64 bits - simple; don't know if it covers all compatibility issues;
> 2. 32 bit compatibility layer (through compat_ioctl, just like many drivers in kernel implement) - just a little bit simple code with some translations; really covers all issues;
>
> Which one is preferred by kernel community?
You shouldn't need to pad paramters in most cases as platform alignment
rules are usually sane for 32 and 64bit. #1 is preferred. #2 exists
because 64bit appeared after Linux was designed so it wasn't designed in
from day one.
next prev parent reply other threads:[~2014-10-28 22:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-26 12:25 32 bit user space compatibility Skidanov, Alexey
2014-10-28 22:34 ` One Thousand Gnomes [this message]
2014-11-03 12:46 ` Yann Droneaud
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