Re: [PATCH] commands/crc32: add compare 2 files crc

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Sep 22, 2010 at 06:12:18PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 18:08 Wed 22 Sep     , Sascha Hauer wrote:
> > On Wed, Sep 22, 2010 at 05:25:49PM +0200, Peter Korsgaard wrote:
> > > >>>>> "Sascha" == Sascha Hauer <s.hauer@pengutronix.de> writes:
> > > 
> > >  Sascha> On Wed, Sep 22, 2010 at 12:36:25PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > >  >> add -F options to compare to file crc
> > >  >> 
> > >  >> it's usefull to compare what you flash in a partition
> > > 
> > >  Sascha> Why don't you use memcmp?
> > > 
> > >  Sascha> memcmp -s uImage -d /dev/nand0.kernel.bb 0 0
> > > 
> > > It's sometimes interesting to be able to compare a checksum with a file
> > > on the host (E.G. output of cksum/md5sum/sha1sum/..)
> > 
> > crc32 can output the crc checksum of a file using the -f option. What
> > Jean-Christophe added is an option to calculate the checksum of two
> > files (one given with -f and the other with -F). I just fail to see why
> > this must be done in a single step instead of using a crc32 followed by
> > a memcmp.
> it's faster btw

Yes, that's the remaining argument, so this should be the selling point
for this patch?

btw, does the patch handle the case when the partition is bigger than
the image file?

I would also write the image file directly to the flash instead of
transfering it to RAM and then copy it to flash. That should be even
faster.

Sascha


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