Re: [PATCH 3/9] Introduce context structure needed during checkpointing/restart

Andrey Mirkin
2008-09-03T14:04:27Z

On Wednesday 03 September 2008 17:56 Louis Rilling wrote:
> On Wed, Sep 03, 2008 at 02:57:50PM +0400, Andrey Mirkin wrote:
> > Add functions for context allocation/destroy.
> > Introduce functions to read/write image.
> > Introduce image header and object header.
>
> [...]
>
> > diff --git a/cpt/cpt_image.h b/cpt/cpt_image.h
> > new file mode 100644
> > index 0000000..3d26229
> > --- /dev/null
> > +++ b/cpt/cpt_image.h
> > @@ -0,0 +1,63 @@
> > +/*
> > + * Copyright (C) 2008 Parallels, Inc.
> > + *
> > + * Author: Andrey Mirkin <major@openvz.org>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License as
> > + * published by the Free Software Foundation, version 2 of the
> > + * License.
> > + *
> > + */
> > +
> > +#ifndef __CPT_IMAGE_H_
> > +#define __CPT_IMAGE_H_ 1
> > +
> > +enum _cpt_object_type
> > +{
> > + CPT_OBJ_TASK = 0,
> > + CPT_OBJ_MAX,
> > + /* The objects above are stored in memory while checkpointing */
> > +
> > + CPT_OBJ_HEAD = 1024,
> > +};
> > +
> > +enum _cpt_content_type {
> > + CPT_CONTENT_VOID,
> > + CPT_CONTENT_ARRAY,
> > + CPT_CONTENT_DATA,
> > + CPT_CONTENT_NAME,
> > + CPT_CONTENT_REF,
> > + CPT_CONTENT_MAX
> > +};
> > +
> > +#define CPT_SIGNATURE0 0x79
> > +#define CPT_SIGNATURE1 0x1c
> > +#define CPT_SIGNATURE2 0x01
> > +#define CPT_SIGNATURE3 0x63
> > +
> > +struct cpt_head
> > +{
> > + __u8 cpt_signature[4]; /* Magic number */
> > + __u32 cpt_hdrlen; /* Header length */
> > + __u16 cpt_image_major; /* Format of this file */
> > + __u16 cpt_image_minor; /* Format of this file */
> > + __u16 cpt_image_sublevel; /* Format of this file */
> > + __u16 cpt_image_extra; /* Format of this file */
> > + __u16 cpt_arch; /* Architecture */
> > + __u16 cpt_pad1;
> > + __u32 cpt_pad2;
> > +#define CPT_ARCH_I386 0
>
> Why is this constant precisely defined after the padding?
I will move it right after cpt_arch. Thanks.

>
> > + __u64 cpt_time; /* Time */
> > +} __attribute__ ((aligned (8)));
> > +
> > +/* Common object header. */
> > +struct cpt_object_hdr
> > +{
> > + __u64 cpt_len; /* Size of current chunk of data */
> > + __u16 cpt_type; /* Type of object */
> > + __u32 cpt_hdrlen; /* Size of header */
> > + __u16 cpt_content; /* Content type: array, reference... */
>
> This layout looks a bit awkward for 32bits/64bits compatibility. Maybe put
> cpt_hdrlen before cpt_type?
You right here. Thanks for the catch. I will change that in next version.

Thanks,
Andrey