Hi Andrew,

After merging the akpm tree, today's linux-next build (powerpc
ppc44x_defconfig) failed like this:

kernel/printk/printk.c: In function 'log_buf_add_cpu':
kernel/printk/printk.c:269:37: error: 'CONFIG_LOG_CPU_MAX_BUF_SHIFT' undeclared (first use in this function)
 #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
                                     ^
kernel/printk/printk.c:864:42: note: in expansion of macro '__LOG_CPU_MAX_BUF_LEN'
  cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
                                          ^
kernel/printk/printk.c:269:37: note: each undeclared identifier is reported only once for each function it appears in
 #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
                                     ^
kernel/printk/printk.c:864:42: note: in expansion of macro '__LOG_CPU_MAX_BUF_LEN'
  cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
                                          ^

Caused by commit 58209adf633e ("printk: allow increasing the ring
buffer depending on the number of CPUs").  CONFIG_LOG_CPU_MAX_BUF_SHIFT
is not defined for this configuration.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au