Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-10-18 11:43, Wen Congyang wrote:
> At 10/18/2011 04:36 PM, Jan Kiszka Write:
>> On 2011-10-18 10:34, Richard W.M. Jones wrote:
>>
>> Yeah, I see. Could also be solved via gdb scripts, but crash is already
>> there.
>>
>> But let's see if the formats actually differ. In the end, crash is just
>> parsing the same information that also gdb sees.
> 
> I think the format can be similar with diskdump/kdump/netdump:
> 
> dump_header:     1 block
> sub header:      n blocks(n is stored in dump_header)
> bitmap:          m blocks(2m is stored in dump_header)
> dumpable bitmap: m blocks
> memory data(We can know whether a page is stored in the core by bitmap and dumpable bitmap)
> 
> The format of dump header(It's like kdump/diskdump):
> struct disk_dump_header {
> 	char			signature[SIG_LEN];	/* = "QEMU    " */
> 	int			header_version; /* Dump header version */
> 	struct new_utsname	utsname;	/* copy of system_utsname */
> 	struct timeval		timestamp;	/* Time stamp */
> 	unsigned int		status;
> 	int			block_size;	/* Size of a block in byte */
> 	int			sub_hdr_size;	/* Size of arch dependent
> 						   header in blocks */
> 	unsigned int		bitmap_blocks;	/* Size of Memory bitmap in
> 						   block */
> 	unsigned int		max_mapnr;	/* = max_mapnr */
> 	unsigned int		total_ram_blocks;/* Number of blocks should be
> 						   written */
> 	unsigned int		device_blocks;	/* Number of total blocks in
> 						 * the dump device */
> 	unsigned int		written_blocks; /* Number of written blocks */
> 	unsigned int		current_cpu;	/* CPU# which handles dump */
> 	int			nr_cpus;	/* Number of CPUs */
> };
> 
> The sub header can contains all registers's value on each vcpu, and other information,
> for example:
> struct qemu_sub_header {
> 	unsigned long	start_pfn;
> 	unsigned long	end_pfn;
> 	off_t		offset_note;
> 	unsigned long	size_note;
> };

So is this a standard format or only "similar" to something? Which tools
will understand it out-of-the-box? If it's not standard, why?

Jan

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