This option will make --dump-dmesg save only the part of the dmesg
buffer since it was last cleared on the crashed kernel (with
dmesg --clear and such) instead of the whole buffer since boot or
wrap-around. It works on kernels with commit f468908bb55a ("printk:
add clear_idx symbol to vmcoreinfo") merged in v4.6 and otherwise
will default to the regular behavior.
Signed-off-by: Ivan Delalande <colona at arista.com>
---
makedumpfile.8 | 8 +++++++-
makedumpfile.c | 21 +++++++++++++++++++--
makedumpfile.h | 3 +++
3 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/makedumpfile.8 b/makedumpfile.8
index 9932364..76a8d6e 100644
--- a/makedumpfile.8
+++ b/makedumpfile.8
@@ -20,7 +20,7 @@ makedumpfile \- make a small dumpfile of kdump
.br
\fBmakedumpfile\fR [\fIOPTION\fR] [\-\-xen-syms \fIXEN-SYMS\fR|\-\-xen-vmcoreinfo \fIVMCOREINFO\fR] \fIVMCORE\fR \fIDUMPFILE\fR
.br
-\fBmakedumpfile\fR \-\-dump-dmesg [\-x \fIVMLINUX\fR|\-i \fIVMCOREINFO\fR] \fIVMCORE\fR \fILOGFILE\fR
+\fBmakedumpfile\fR \-\-dump-dmesg [\-\-partial-dmesg] [\-x \fIVMLINUX\fR|\-i \fIVMCOREINFO\fR] \fIVMCORE\fR \fILOGFILE\fR
.br
\fBmakedumpfile\fR [\fIOPTION\fR] \-x \fIVMLINUX\fR \-\-diskset=\fIVMCORE1\fR \-\-diskset=\fIVMCORE2\fR [\-\-diskset=\fIVMCORE3\fR ..] \fIDUMPFILE\fR
.br
@@ -586,6 +586,12 @@ it is necessary to specfiy [\-x \fIVMLINUX\fR] or [\-i \fIVMCOREINFO\fR].
.TP
+\fB\-\-partial-dmesg\fR
+This option will make --dump-dmesg extract only dmesg logs since that buffer was
+last cleared on the crashed kernel, through "dmesg --clear" for example.
+
+
+.TP
\fB\-\-mem-usage\fR
This option is only for x86_64.
This option is used to show the page numbers of current system in different
diff --git a/makedumpfile.c b/makedumpfile.c
index 95cc5ef..7c88203 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -1498,6 +1498,7 @@ get_symbol_info(void)
SYMBOL_INIT(log_buf_len, "log_buf_len");
SYMBOL_INIT(log_end, "log_end");
SYMBOL_INIT(log_first_idx, "log_first_idx");
+ SYMBOL_INIT(clear_idx, "clear_idx");
SYMBOL_INIT(log_next_idx, "log_next_idx");
SYMBOL_INIT(max_pfn, "max_pfn");
SYMBOL_INIT(modules, "modules");
@@ -2115,6 +2116,7 @@ write_vmcoreinfo_data(void)
WRITE_SYMBOL("log_buf_len", log_buf_len);
WRITE_SYMBOL("log_end", log_end);
WRITE_SYMBOL("log_first_idx", log_first_idx);
+ WRITE_SYMBOL("clear_idx", clear_idx);
WRITE_SYMBOL("log_next_idx", log_next_idx);
WRITE_SYMBOL("max_pfn", max_pfn);
WRITE_SYMBOL("high_memory", high_memory);
@@ -2509,6 +2511,7 @@ read_vmcoreinfo(void)
READ_SYMBOL("log_buf_len", log_buf_len);
READ_SYMBOL("log_end", log_end);
READ_SYMBOL("log_first_idx", log_first_idx);
+ READ_SYMBOL("clear_idx", clear_idx);
READ_SYMBOL("log_next_idx", log_next_idx);
READ_SYMBOL("max_pfn", max_pfn);
READ_SYMBOL("high_memory", high_memory);
@@ -5025,6 +5028,7 @@ dump_dmesg()
int log_buf_len, length_log, length_oldlog, ret = FALSE;
unsigned long index, log_buf, log_end;
unsigned int idx, log_first_idx, log_next_idx;
+ unsigned long long first_idx_sym;
unsigned long log_end_2_6_24;
unsigned log_end_2_6_25;
char *log_buffer = NULL, *log_ptr = NULL;
@@ -5058,7 +5062,13 @@ dump_dmesg()
ERRMSG("Can't find variable-length record symbols");
return FALSE;
} else {
- if (!readmem(VADDR, SYMBOL(log_first_idx), &log_first_idx,
+ if (info->flag_partial_dmesg
+ && SYMBOL(clear_idx) != NOT_FOUND_SYMBOL)
+ first_idx_sym = SYMBOL(clear_idx);
+ else
+ first_idx_sym = SYMBOL(log_first_idx);
+
+ if (!readmem(VADDR, first_idx_sym, &log_first_idx,
sizeof(log_first_idx))) {
ERRMSG("Can't get log_first_idx.\n");
return FALSE;
@@ -5102,7 +5112,10 @@ dump_dmesg()
DEBUG_MSG("log_buf : %lx\n", log_buf);
DEBUG_MSG("log_end : %lx\n", log_end);
DEBUG_MSG("log_buf_len : %d\n", log_buf_len);
- DEBUG_MSG("log_first_idx : %u\n", log_first_idx);
+ if (info->flag_partial_dmesg)
+ DEBUG_MSG("clear_idx : %u\n", log_first_idx);
+ else
+ DEBUG_MSG("log_first_idx : %u\n", log_first_idx);
DEBUG_MSG("log_next_idx : %u\n", log_next_idx);
if ((log_buffer = malloc(log_buf_len)) == NULL) {
@@ -11022,6 +11035,7 @@ static struct option longopts[] = {
{"message-level", required_argument, NULL, OPT_MESSAGE_LEVEL},
{"vtop", required_argument, NULL, OPT_VTOP},
{"dump-dmesg", no_argument, NULL, OPT_DUMP_DMESG},
+ {"partial-dmesg", no_argument, NULL, OPT_PARTIAL_DMESG},
{"config", required_argument, NULL, OPT_CONFIG},
{"help", no_argument, NULL, OPT_HELP},
{"diskset", required_argument, NULL, OPT_DISKSET},
@@ -11135,6 +11149,9 @@ main(int argc, char *argv[])
case OPT_DUMP_DMESG:
info->flag_dmesg = 1;
break;
+ case OPT_PARTIAL_DMESG:
+ info->flag_partial_dmesg = 1;
+ break;
case OPT_MEM_USAGE:
info->flag_mem_usage = 1;
break;
diff --git a/makedumpfile.h b/makedumpfile.h
index 6ea8cc4..d3b7532 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -1241,6 +1241,7 @@ struct DumpInfo {
int flag_force; /* overwrite existing stuff */
int flag_exclude_xen_dom;/* exclude Domain-U from xen-kdump */
int flag_dmesg; /* dump the dmesg log out of the vmcore file */
+ int flag_partial_dmesg; /* dmesg dump only from the last cleared index*/
int flag_mem_usage; /*show the page number of memory in different use*/
int flag_use_printk_log; /* did we read printk_log symbol name? */
int flag_nospace; /* the flag of "No space on device" error */
@@ -1529,6 +1530,7 @@ struct symbol_table {
unsigned long long log_buf_len;
unsigned long long log_end;
unsigned long long log_first_idx;
+ unsigned long long clear_idx;
unsigned long long log_next_idx;
unsigned long long max_pfn;
unsigned long long node_remap_start_vaddr;
@@ -2268,6 +2270,7 @@ struct elf_prstatus {
#define OPT_SPLITBLOCK_SIZE OPT_START+14
#define OPT_WORKING_DIR OPT_START+15
#define OPT_NUM_THREADS OPT_START+16
+#define OPT_PARTIAL_DMESG OPT_START+17
/*
* Function Prototype.
--
2.13.1
--
Ivan Delalande
Kernel Team - Vancouver - #? A3Y20
Phone: 7342 | Mobile: 604 600 5313
