Re: [microblaze-uclinux] Uart lite hanging

["Kristoffer Hedberg" <grim@xxxxxxxxxxxxxxxx>]

Hi Giulio,

We have experienced the exact same symptoms. In our case, it can either be
writing to the console UART or one of the other UARTs we have in our
configuration that causes this kind of behaviour. The problem manifests
itself in the same way, i.e. the program hangs and begins to converge to
100% CPU usage.

Regards,

Kristoffer Hedberg

> I really don't know what to think.
>
> I tried writing a new serial driver from scratch.
> I decided not to use the tty subsystem and preferred passing data
> from/to userland via proc interface.
> It uses internal circular buffers to store ingoing and outgoing chars.
> Even if my driver is very badly written it works for test purposes.
> I brought up a loopback test that passed.
>
> After that I simply added a 100 sprintf statement in a for loop and I
> was still able to hang the application (or the thread in case of a
> multi-threaded program) on the usual instruction 0x44001e08 (0x44000000
> is my ram base address), out of the process text segment, by just doing
> cut & paste from a serial console in minicom.
> The device is open in write only mode.
>
> While the application is hanged the cpu usage starts growing up and irqs
> from the serial line are still acknowledged correctly (the rx in this
> case because of the cut & paste operation).
>
> If I discover anything else I'll let you know.
>
> I would be very glad if anybody would spend a minute to try my test
> (included in the previous message) and send me a feedback.
>
> Many thanks,
> Giulio Mazzoleni
>
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