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hw/misc: add vmcoreinfo device

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See docs/specs/vmcoreinfo.txt for details.

"etc/vmcoreinfo" fw_cfg entry is added when using "-device vmcoreinfo".

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marc-André Lureau 2017-09-11 18:59:24 +02:00 • committed by Michael S. Tsirkin
parent 5f9252f7cc
commit 6e43353f10
4 changed files with 184 additions and 0 deletions
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docs/specs/vmcoreinfo.txt Normal file
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=================
VMCoreInfo device
=================
The `-device vmcoreinfo` will create a fw_cfg entry for a guest to
store dump details.
etc/vmcoreinfo
**************
A guest may use this fw_cfg entry to add information details to qemu
dumps.
The entry of 16 bytes has the following layout, in little-endian::
#define VMCOREINFO_FORMAT_NONE 0x0
#define VMCOREINFO_FORMAT_ELF 0x1
struct FWCfgVMCoreInfo {
uint16_t host_format; /* formats host supports */
uint16_t guest_format; /* format guest supplies */
uint32_t size; /* size of vmcoreinfo region */
uint64_t paddr; /* physical address of vmcoreinfo region */
};
Only full write (of 16 bytes) are considered valid for further
processing of entry values.
A write of 0 in guest_format will disable further processing of
vmcoreinfo entry values & content.
Format & content
****************
As of qemu 2.11, only VMCOREINFO_FORMAT_ELF is supported.
The entry gives location and size of an ELF note that is appended in
qemu dumps.
The note format/class must be of the target bitness and the size must
be less than 1Mb.