On 10/18/2011 09:55 PM, Jan Kiszka wrote:
On 2011-10-18 15:51, Wen Congyang wrote:
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.
The format crash already processes? What do you need in addition? That
should be discussed first, not the format details.
A way to dump the memory to a file, and crash can analyze it. We always
use crash
to analyze such file because it is easier than gdb to use.
We can use 'virsh dump' to dump the memory to a file, but 'virsh dump'
can not
work while host pci device is used by guest(The reason is that 'virsh
dump' uses
monitor command migrate to dump the memory to a file).
gdbserver is not the way need, because the guest should be restarted
quickly.
I think introducing a new monitor command(named dump) to do such thing,
and you
have agreed it in another mail.
I first to try to reuse migration's code, but I meet some problem(I have
pointed it
out in an early mail today).
You advice me to reuse gdbstub's code, but I think crash can not support
such format.
And I want to implement it without reusing any other codes in qemu(If
so, we should determine
the core's format).
I am happy if you have some other ideas.
Thanks
Wen Congyang
Jan
