Re: [Xen-devel] [PATCH][TOOLS] libfsimage: make pygrub work on ufs

[Christoph Egger <Christoph.Egger@xxxxxxx>]

On Tuesday 10 June 2008 13:40:57 John Levon wrote:
> On Tue, Jun 10, 2008 at 10:24:56AM +0200, Christoph Egger wrote:
> > > > @@ -32,8 +32,9 @@
> > > >  #define SUPERBLOCK ((struct fs *)(FSYS_BUF + 0x2000))
> > > >  #define        INODE ((struct icommon *)(FSYS_BUF + 0x1000))
> > > >  #define DIRENT (FSYS_BUF + 0x4000)
> > > > +#define MAXBSIZE ((FSYS_BUFLEN - 0x4000) / 2)
> > > >  #define INDIRBLK1 ((grub_daddr32_t *)(FSYS_BUF + 0x4000)) /* 2+
> > > > indirblk
> >
> > */
> >
> > > >  -#define       INDIRBLK0 ((grub_daddr32_t *)(FSYS_BUF+ 0x6000))  /* 1st
> >
> > indirect blk */
> >
> > > > +#define        INDIRBLK0 ((grub_daddr32_t *)(FSYS_BUF+ 0x4000 + 
> > > > MAXBSIZE)) 
> > > > /*
> >
> > 1st indirect blk */
> >
> > > This is a no-op, right?
> >
> > No, FSYS_BUFLEN is used now which wasn't before.
>
> Ooops, I mis-read the value of FSYS_BUFLEN. So you need this because
> indirect blocks don't fit in the original space available?

Yes. Also to reach alternative/other superblocks. Just imagine, the guest 
crashed and the filesystem wasn't cleanly unmounted.

Christoph

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Operating System Research Center

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