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authorMarc-André Lureau <marcandre.lureau@redhat.com>2017-09-11 18:59:24 +0200
committerMichael S. Tsirkin <mst@redhat.com>2017-10-15 05:54:40 +0300
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hw/misc: add vmcoreinfo device
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>
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diff --git a/docs/specs/vmcoreinfo.txt b/docs/specs/vmcoreinfo.txt
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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.