Re: [MiNT] FreeMiNT & MiNTlib patchset - add new support

[Alan Hourihane <alanh@fairlite.co.uk>]

On Wed, 2008-08-20 at 10:27 +0200, Frank Naumann wrote:
> Hello Alan!
> 
> > Ah, excellent. Looks like we can bump the version already as version
> > incompatibilities have arisen in the past and code is there to already
> > support this.
> >
> > In sys/xfs/ext2/main.c I can see MSG_OLDMINT which we can bump for the
> > XFS module. minixfs has something similar.
> >
> > But it's what to do in the kernel when loading older XFS modules ?
> > Frank ?
> 
> This is not supported (e.g. the kernel always load the xfs/xdd; only the 
> modules have a version check).
> 
> >>> Yes, I took a deeper look into the code. It looks good.
> >>>
> >>> A question about this (I don't checked it): it is possible to catch
> >>> read/write request at a igher level instead inside the xfs? This make much
> >>> more sense (and avoid the problem if a newer kernel load an older xfs).
> 
> That's what I meant. I like to move the EISDIR error check into the 
> filesystem layer. And, if this is possible (not checked), the open() on 
> the directory shall be handled at the filesystem layer too.
> 
> >> Oh, and as for loading older XFS modules. That's not going to work
> >> really, as we're going to be allowing a read-only directory through to
> >> the XFS. Older XFS's don't understand that.
> 
> This avoid any modification on the xfs, we don't have any compatibility 
> problems and the directories are handled generically inside the kernel.

Without adding a new flag to the XFS module to detect an older XFS, I'm
not sure how adding additional checks for EISDIR into the kernel
filesystem layer can help.

Alan.