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Date: Thu, 30 Jul 2009 18:53:30 +0200
Message-ID: <7c86c4470907300953g255c6088t7caaa1188be164e3@mail.gmail.com>
Subject: Re: I.1 - System calls - ioctl
From: stephane eranian <eranian@googlemail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Christoph Hellwig <hch@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       LKML <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Robert Richter <robert.richter@amd.com>,
       Paul Mackerras <paulus@samba.org>, Andi Kleen <andi@firstfloor.org>,
       Maynard Johnson <mpjohn@us.ibm.com>, Carl Love <cel@us.ibm.com>,
       Corey J Ashford <cjashfor@us.ibm.com>,
       Philip Mucci <mucci@eecs.utk.edu>, Dan Terpstra <terpstra@eecs.utk.edu>,
       perfmon2-devel <perfmon2-devel@lists.sourceforge.net>
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On Thu, Jul 30, 2009 at 6:40 PM, Arnd Bergmann<arnd@arndb.de> wrote:
> On Thursday 30 July 2009, stephane eranian wrote:
>> long sys_perf_counter_open(
>>        struct perf_counter_attr *attr,
>>        enum perf_target_type  target_type,
>>        int target_id,
>>        int group_fd,
>>        unsigned long flags);
>>
>> Which is what you had, except without the struct.
>>
>> Then, it boils down to whether expressing a target id in 32 bits is enough.
>> Obviously, 64-bit would be the safest but then I understand this causes issues
>> on 32-bit systems.
>
> Just make it an unsigned long then, that still covers all cases
> where you only need the 64-bit type on 64-bit systems.
>
But that won't always work in the case of a 32-bit monitoring tool
running on top of
a 64-bit OS. Imagine the target id is indeed 64-bit, e.g., inode
number (as suggested
by Peter). It's not because you are a 32-bit tool than you cannot name
a monitoring
resource in a 64-bit OS.


>        Arnd <><
>
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