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

[Wen Congyang <wencongyang@gmail.com>]

On 10/18/2011 06:28 PM, Jan Kiszka wrote:
> 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?

Only similar to something, and we can add a little codes into crash to 
support such format.

If you have a better format, please tell me.

Thanks
Wen Congyang

>
> Jan
>