Re: [Qemu-devel] Questions regarding emulated UART in VersatilePB board

[Ramy Sameh]

Thanks Peter.

I have made a program to read a string from the UART, then write it again
to the UART.
I made a function to manipulate values in the pl011 registers (bit flipping
the flags inside the registers).
The target is to simulate hardware fault injection.

For each run of the program, I made a bit-flip in *only one flag* in *one
register*, and I observed the output of the program.

*My question is*: where to invoke the call of this fault injection function
to cause *the maximum effect* on the program's output?

*p.s.* I invoked it once inside pl011_read function, and the program gave a
certain output, and I invoked it again in pl011_update, and it gave another
output.
When I invoked the function in pl011_write, the faults injected had no
effect on the output of the program!

Do you have an explanation for this behaviour?

Thanks in advance.


On Wed, Sep 6, 2017 at 2:18 PM, Peter Maydell <address@hidden>
wrote:

> On 6 September 2017 at 13:12, Ramy Sameh <address@hidden> wrote:
> > Do the emulated baud rate registers have any effect? (I think they would
> > have no effect, because there is no real clock that can be used to
> produce
> > the baud rate).
>
> No, they don't have any effect. (In this UART model we don't implement
> the feature that you can connect a guest serial port to a host serial
> port and have the guest baud rate etc settings propagate through.
> We do that in other UART models and maybe one day we'll add it here,
> but for now, baud rate settings are ignored.)
>
> thanks
> -- PMM
>



-- 
Best Regards,
Ramy Sameh
Embedded Software Engineer
+2-010-172-777-14