From 42955c0b4d9c0723de72a810f80e4b3543053631 Mon Sep 17 00:00:00 2001
From: Kazuhito Hagio <k-hagio-ab@nec.com>
Date: Wed, 30 Nov 2022 12:02:44 +0900
Subject: [PATCH 3/7] [PATCH] IMPLEMENTAION: Add a description of the flattened
format
Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
---
IMPLEMENTATION | 45 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/makedumpfile-1.7.2/IMPLEMENTATION b/makedumpfile-1.7.2/IMPLEMENTATION
index 589c5bf..b7a1603 100644
--- a/makedumpfile-1.7.2/IMPLEMENTATION
+++ b/makedumpfile-1.7.2/IMPLEMENTATION
@@ -280,3 +280,48 @@
If there is no segment dumped into the DUMPFILE, the DUMPFILE can't be
analysed by crash.
+
+
+* The flattened format
+
+ This format is mostly used to send dump data to a remote host via SSH.
+ The kdump-compressed format and ELF format require random access to create
+ a DUMPFILE, so it cannot be written directly to standard output.
+ The flattened format adds the original offset and size of each data block,
+ and it can be rearranged to the original format on the remote host.
+
+ - File structure
+
+ This is the case of the kdump-compressed format.
+ File offset
+ +------------------------------------------+ 0x0
+ | flat header (struct makedumpfile_header) |
+ | |
+ |------------------------------------------| 0x1000 (4096)
+ | flat data header |
+ | (struct makedumpfile_data_header) |
+ | main header (struct disk_dump_header) |
+ |------------------------------------------| (not aligned)
+ | flat data header |
+ | : |
+
+ Note: For the ELF format, ELF header is not always the first data.
+
+ - flat header
+
+ struct makedumpfile_header {
+ char signature[SIG_LEN_MDF]; /* = "makedumpfile\0\0\0\0" */
+ int64_t type; /* = TYPE_FLAT_HEADER (1) */
+ int64_t version; /* = VERSION_FLAT_HEADER (1) */
+ };
+
+ Note: the type and version are big endian.
+
+ - flat data header
+
+ struct makedumpfile_data_header {
+ int64_t offset;
+ int64_t buf_size;
+ };
+
+ Note: the offset and buf_size are big endian.
--
2.33.1