Re: [PATCH v6 01/24] erofs: add on-disk layout
From: Pavel Machek
Date: Tue Sep 03 2019 - 07:27:14 EST
> > No. gdb tells you what the actual offsets _are_.
> Ok, reading your reply twice, I think we have different perspectives. I
> don't trust the comments.
> The tool I had in mind is pahole that parses dwarf information about the
> structures, the same as gdb does. The actual value of the struct members
> is the thing that needs to be investigated in memory dumps or disk image
> > > > The expected offset is somewhat valuable, but
> > > > perhaps the form is a bit off given the visual
> > > > run-in to the field types.
> > > >
> > > > The extra work with this form is manipulating all
> > > > the offsets whenever a structure change occurs.
> > >
> > > ... while this is error prone.
> > While the comment tells you what they _should be_.
> That's exactly the source of confusion and bugs. For me an acceptable
> way of asserting that a value has certain offset is a build check, eg.
> BUILD_BUG_ON(strct my_superblock, magic, 16);
Yes, that would work, too. As would documentation file with the disk
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Description: Digital signature