[PATCH] Add the --partial-dmesg option to dump only non-cleared dmesg
Atsushi Kumagai
ats-kumagai at wm.jp.nec.com
Mon Jun 12 23:20:57 PDT 2017
Hello Ivan,
>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.
It works fine, thanks.
I think check_param_for_creating_dumpfile() should be modified
to reject a single --partial-dmesg, it should be always specified
with --dump-dmesg.
Thanks,
Atsushi Kumagai
>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 - #³ A3Y20
>Phone: 7342 | Mobile: 604 600 5313
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