Ingvald Gjesdal wrote:
>
> In an embedded project I use ttyS0 as the only console. There is no video
> controller and no keyboard in the system.
>
> The problem is that /dev/console and /dev/ttyS0 output is _very_ slow: 16
> bytes are sent, then Linux pauses for about 10 sec and the next block of 16
> bytes is sent. (It looks like the interrupt is disabled and the device
> driver polls the uart every 10 sec). Error messages from the kernel is sent
> at the normal speed.
>
> Does anybody know the reason for this problem?
I have had the same problem on the built-in serial interface of an AMD �lan
SC410 CPU.
It turned out to be a bug in AMD's 8250 emulation, which caused the THRE bit in
the LSR to be set one bit-time *after* the interrupt was generated, instead of
simultaneously.
This, in turn, causes the interrupt service routine in serial.c to ignore the Tx
interrupt.
I have patches ready for the AMD SC4x0 bug - please let me know if you are using
the same (or a similar AMD) CPU and, if yes, which kernel version you are using.
--
cheers
Anders Larsen
Q: What does the CE in Windows CE stand for?
A: Caveat Emptor
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