On Mon, Jan 05, 2015 at 10:19:25AM -0500, Steven Rostedt wrote:

On Mon,  5 Jan 2015 14:54:58 +0000
Daniel Thompson [off-list ref] wrote:

quoted

+/* For reliability, we're prepared to waste bits here. */
+static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
+static  cpumask_t printtrace_mask;
+
+#define NMI_BUF_SIZE		4096
+
+struct nmi_seq_buf {
+	unsigned char		buffer[NMI_BUF_SIZE];
+	struct seq_buf		seq;
+};

Am I missing something or does this limit us to 4096 characters of
backtrace output per CPU?

This is the same code as in x86. I wonder if we should move the
duplicate code into kernel/printk/ and have it compiled if the arch
requests it (CONFIG_ARCH_WANT_NMI_PRINTK or something). That way we
don't have 20 copies of the same nmi_vprintk() and later find that we
need to change it, and have to change it in 20 different archs.

Agreed, though I wonder about the buffer size.

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