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

[Ramy Sameh]

Hello Peter,

Any suggestions regarding this topic ?

On Sun, Sep 10, 2017 at 8:33 PM, Ramy Sameh <address@hidden> wrote:

> 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
>



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