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Date: Wed, 10 Sep 2008 21:04:01 +0300
From: Boaz Harrosh <bharrosh@panasas.com>
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To: Chris Leech <christopher.leech@intel.com>
CC: Dave Kleikamp <shaggy@linux.vnet.ibm.com>,
       Christoph Hellwig <hch@infradead.org>,
       jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org,
       linux-scsi@vger.kernel.org
Subject: Re: [Open-FCoE] [PATCH 1/3] 24-bit types: typedef and macros for
 accessing 3-byte arrays as integers
References: <20080905165732.16689.50256.stgit@localhost.localdomain>		<20080910140712.GA12280@infradead.org>	<1221061241.27385.14.camel@norville.austin.ibm.com> <48C7F4EC.1080709@intel.com> <48C807A9.60509@intel.com>
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Chris Leech wrote:
> Chris Leech wrote:
>> Dave Kleikamp wrote:
>>> @@ -62,7 +60,7 @@ struct timestruc_t {
>>>   */
>>>  typedef struct {
>>>  	unsigned len:24;
>>> -	unsigned off1:8;
>>> +	u8 off1;
>>>  	u32 off2;
>>>  } lxd_t;
>> Shouldn't len here be changed to a __le24?  I think this just changed
>> the size of lxd_t by a byte.
> 
> Never mind, I see that it's a host order field.  And presently surprised
> to see that gcc combines the 24-bit bitfield with the following u8.
> 
> Chris

It does because these are all bytes. on x86. But this is not guarantied
for all ARCHs and machine-word-sizes. In any way this should be consistent
with the rest of the file.

Please see my other reply about packing of structures. If this is
on-the-wire then there are problems.

Boaz