Date: Tue,  5 Nov 2024 15:59:32 +1300
From: Tao Liu <ltao@redhat.com>
Subject: [Crash-utility] [PATCH] Mark --log option as deprecated
To: devel@lists.crash-utility.osci.io
Cc: Tao Liu <ltao@redhat.com>
Message-ID: <20241105025932.59489-1-ltao@redhat.com>
Content-Type: text/plain; charset="US-ASCII"; x-default=true

Since kernel(>=v5.10), a new lockless ringbuffer is introduced. And
crash commit a5531b24 ("printk: add support for lockless ringbuffer")
implemented the lockless ringbuffer dumping for cmd_log, this however,
relies on the existence of kernel debuginfo.

Since there is already a similar function been implemented for
makedumpfile, aka "makedumpfile --dump-dmesg" to dump dmesg logs with
only vmcore, there is no need to maintain a similar code in crash
as well. In addition, this option is not widely used, so just mark
"--log" option as deprecated for crash.

Signed-off-by: Tao Liu <ltao@redhat.com>
---
 crash.8 | 4 +++-
 help.c  | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/crash.8 b/crash.8
index 0662f92..6abd381 100644
--- a/crash.8
+++ b/crash.8
@@ -333,10 +333,12 @@ or
 .I /proc/kcore
 devices.
 .TP
-.BI --log \ dumpfile
+.BI --log \ dumpfile \ (deprecated)
 Dump the contents of the kernel log buffer.  A kernel namelist
 argument is not necessary, but the dumpfile must contain the
 VMCOREINFO data taken from the original /proc/vmcore ELF header.
+Note: this option is deprecated and will no longer work for
+kernel(>=v5.10), use "makedumpfile --dump-dmesg" instead.
 .TP
 .B --no_kallsyms
 Do not use kallsyms-generated symbol information contained within
diff --git a/help.c b/help.c
index e95ac1d..caf52f5 100644
--- a/help.c
+++ b/help.c
@@ -211,10 +211,12 @@ char *program_usage_info[] = {
     "    Use device as an alternative device to the /dev/crash, /dev/mem",
     "    or /proc/kcore devices.",
     "",
-    "  --log dumpfile",
+    "  --log dumpfile (deprecated)",
     "    Dump the contents of the kernel log buffer.  A kernel namelist",
     "    argument is not necessary, but the dumpfile must contain the",
     "    VMCOREINFO data taken from the original /proc/vmcore ELF header.",
+    "    Note: this option is deprecated and will no longer work for",
+    "    kernel(>=v5.10), use \"makedumpfile --dump-dmesg\" instead.",
     "",
     "  --no_kallsyms",
     "    Do not use kallsyms-generated symbol information contained within",
--
2.47.0