Re: [PATCH] Endianness-aware mkcramfs

["H. Peter Anvin" <hpa@zytor.com>]

Jeremy Puhlman wrote:

> On Tue, Dec 04, 2001 at 04:49:41PM -0800, Matthew Dharm wrote:
> 
>>There is another argument for supporting both endiannesses....
>>
>>Consider an embedded system which can be run in either endianness.  Sounds
>>silly?  MIPS processors can run big or little endian, and many people
>>routinely switch between them.
>>
> Yes but typically this also includes a step of reflashing firmware or
> swaping of firmware...So it would not be unrealistic to swap out the
> filesystem as well...
> 
> Since in a deployment situation you will always be sticking with one endianness 
> it makes sense that you would want the most speed for your buck...Since flash 
> filesystems are slow to begin with also adding in the decompression
> hit you get from cramfs...it would seem to me that adding in le<->be
> would just add to its speed reduction....That would seem to be a good
> place to trim the fat so to speak...
> 


Actually, you've got it completely backwards.  Because the compression
system used (deflate) is endian-independent, the only thing in cramfs that
is endian-sensitive is the metadata.  Byteswapping the metadata is
probably not a measurable performance effect.

	-hpa