On 9 May 2003, Greg Troxel wrote:

> I have had this problem as well.  My box is a Thinkpad 600 (233 MHz)
> with
>   com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, working fifo
>
> It runs 1.6.1 and pppd with a 28.8k modem at 57600 on the serial port
> and a USB ethernet.  Most of the time I get very few errors, but when
> I left myself logged in to the console (X11) I got a lot.  Typical
> errors are:
>
> com0: 6 silo overflows, 0 ibuf floods
> com0: 4 silo overflows, 0 ibuf floods
> com0: 4 silo overflows, 0 ibuf floods
> com0: 11 silo overflows, 0 ibuf floods
> com0: 16 silo overflows, 0 ibuf floods
> com0: 1 silo overflow, 0 ibuf floods
>
> which cause PPP FCS/framing errors.

exactly, and since my link is slow enough already it doesnt help..

> I am fairly sure there is no MP code in 1.6.1, but that doesn't mean
> no changes were made for finer-grained locking.

I could re-install the 1.6 sources and check what changed, but where to
look?

> Are you running X?

Yes, but it does seem to happen even if I just sit there and watch it,
whereas with the 1.6 kernel I can run a hefty compile with no troubles, so
I cant see that its the processor not being able to keep up.

> It would be cool to have an interrupt priority level trace facility
> that logged levels and cycle counter times.  This would pretty clearly
> have to be a special compile of the kernel to replace/adjust the spl()
> calls and catch interrupt-routine entry/exit.

whoosh, over my head, sorry :)

iain

should I send-pr this? I didnt because I cant really provide much in the
way of examples or fixes, but there seem to be a few people with the same
problem..