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

Louis Rilling
2008-09-03T13:56:26Z

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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?

> + __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?

Louis

--
Dr Louis Rilling Kerlabs
Skype: louis.rilling Batiment Germanium
Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes
http://www.kerlabs.com/ 35700 Rennes

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