On 04/07/2013 23:20, Andreas Nilsson wrote:
On Sun, Apr 7, 2013 at 9:36 PM, deeptech71 <[email protected]
<mailto:[email protected]>> wrote:
options PRINTF_BUFR_SIZE=128 # Prevent printf output being interspersed.
And here I thought that it was added to mitigate the "interspersed output"
problem, and I remember that adding to the conf on previous version help address the
problem.
And you were right. AFAICT, the problem was that the threads were writing single
characters ("putc()ing") at a time, and would get preempted by other such
threads in between. Thus, such tasks would get interleaved at character granularity.
Proposals were:
(a) use a stack array in printf()'s body to do line buffering; some argued
that kernel stack sizes are fairly limited, others argued that this should not
be a limitation even on embedded platforms;
(b) allow a printf() task to fully finish before allowing other printf()
tasks to start.
The (a) solution was chosen, with an amendment that the array would be specifiable by a
kernel configuration option. GENERIC kernels have "options
PRINTF_BUFR_SIZE=128".
If the original poster had removed the PRINTF_BUFR_SIZE option from his kernel
configuration, then I see his complaint as invalid.
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