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

[Louis Rilling]

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@xxxxxxxxxx>
> + *
> + *  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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