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

[Wen Congyang <wency@cn.fujitsu.com>]

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;
};

Thanks
Wen Congyang

> 
> Jan
>