Subject: Re: [PATCH] ixgbe: Introduce new 10GbE driver for Intel 82598 based PCI Express adapters...

From: Jeff Garzik <[email-masked]>
Date: Thu, 05 Jul 2007 19:29:01 -0400

Inaky Perez-Gonzalez wrote:
> On Tuesday 03 July 2007, Jeff Garzik wrote:
>> Inaky Perez-Gonzalez wrote:
>> Access to bitfields are not atomic within the machine int in which they 
>> are stored... you need to "unpack" the values stored in bitfields, even 
>> if they are single-bit bitfields.
> 
> Which we do manually when we don't use bitfields. Again, conceptually,
> there is no difference.

Practically speaking -- there are differences.

The "manual" method hides nothing from the programmer, while use of 
bitfields hides the lack of atomicity.

When you have programmers who make mistakes -- i.e. real humans -- these 
things matter.

But overall, it is not any one detail that discourages use of bitfields; 
it is the sum of all the reasons.  Practical experience, compiler 
technology, mistakes made (and not made), all point to avoiding bitfields.

	Jeff