<div dir="ltr">Hello Alexander,<div class="gmail_extra"><br><div class="gmail_quote">On Sat, Jul 18, 2015 at 11:23 AM, Alexander <span dir="ltr"><<a href="mailto:alexhoppus111@gmail.com" target="_blank">alexhoppus111@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><br>
Hi!<br>
When i checked how kernel printing works, i mentioned that it takes messages<br>
from log_buffer in console_unlock and gives it to call_console_drivers -> ...<br>
-> some uart bsp function. Basically, as i see this BSP realization tries<br>
to flush all message chars in busyloop ... so it waits until FIFO_NOT_FULL bit will<br>
be dropped by UART and it will be able to push the next byte.<br>
Basically, as i see userspace printing do something different. It puts N_FIFO_BYTES<br>
and exits, next, when FIFO will be freed - interrupt will be generated, and<br>
other characters will be put into UART FIFO.<br>
Can we do something similar for kernel printing? i.e. do not busyloop sending char<br>
after char, but put N_FIFO chars and flush other in interrupt. When panic will occur<br>
we can do busyloop printing again. Is it reliable? Suppose we have several cores.<br>
Thank you.<br></blockquote><div>What about trying this patch,</div><div><a href="https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/kernel/printk/printk.c?id=5874af2003b1aaaa053128d655710140e3187226">https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/kernel/printk/printk.c?id=5874af2003b1aaaa053128d655710140e3187226</a></div><div><br></div><div>Its not changing console printing through UART to interrupt mode. But minimizes the time interrupts being disabled on printk().</div><div><br></div><div>Thanks,</div><div>Arun</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<span class=""><font color="#888888"><br>
--<br>
Alexander <<a href="mailto:alexhoppus111@gmail.com">alexhoppus111@gmail.com</a>><br>
<br>
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