Messages in this thread | | | Date | Fri, 9 Jan 2015 16:48:01 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 3.19-rc2 v13 4/5] ARM: Add support for on-demand backtrace of other CPUs |
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On Mon, Jan 05, 2015 at 10:19:25AM -0500, Steven Rostedt wrote: > On Mon, 5 Jan 2015 14:54:58 +0000 > Daniel Thompson <daniel.thompson@linaro.org> wrote: > > +/* 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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