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From: Alexander Graf <graf@amazon.com>
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Subject: [PATCH v3 16/17] tracing: Add config option for kexec handover
Date: Wed, 17 Jan 2024 14:47:03 +0000
Message-ID: <20240117144704.602-17-graf@amazon.com>
In-Reply-To: <20240117144704.602-1-graf@amazon.com>
References: <20240117144704.602-1-graf@amazon.com>
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Now that all bits are in place to allow ftrace to pass its trace data
into the next kernel on kexec, let's give users a kconfig option to
enable the functionality.

Signed-off-by: Alexander Graf <graf@amazon.com>

---

v1 -> v2:

  - Select crc32
---
 kernel/trace/Kconfig | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 61c541c36596..418a5ae11aac 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -1169,6 +1169,20 @@ config HIST_TRIGGERS_DEBUG
 
           If unsure, say N.
 
+config FTRACE_KHO
+	bool "Ftrace Kexec handover support"
+	depends on KEXEC_KHO
+	select CRC32
+	help
+          Enable support for ftrace to pass metadata across kexec so the new
+	  kernel continues to use the previous kernel's trace buffers.
+
+	  This can be useful when debugging kexec performance or correctness
+	  issues: The new kernel can dump the old kernel's trace buffer which
+	  contains all events until reboot.
+
+	  If unsure, say N.
+
 source "kernel/trace/rv/Kconfig"
 
 endif # FTRACE
-- 
2.40.1


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