Re: [Qemu-devel] [Bug 1630723] [NEW] UART writes to netduino2/stm32f205-soc disappear

[Alistair Francis]

On Fri, Oct 7, 2016 at 8:59 AM, Seth K <address@hidden> wrote:
> The only machine I saw listed in the help output is "netduino2." I pulled
> QEMU from github, was that the right thing to do?
>
> I found the specifications for the stm32f2xx and some similar chips and
> verified the addresses and interrupts are correct.

Sorry my mistake. It is a the Netduino 2 Plus that we don't support.

I think we should move this conversation to the bug report as well, I
was hoping that replying to the email would update the bug report but
it doesn't look like it.

>
> The stm32f205 should support 6 UARTs, and the 6 addresses and IRQs are coded
> correctly. However there is a hard-coded value MAX_SERIAL_PORTS limiting
> serial_hds to 4, and I don't know why. I am considering submitting a patch.

I'm not sure why we have that limit, you can submit a patch and see
what everyone says.

>
> If I increase MAX_SERIAL_PORTS I can write to UARTs 1, 4, 5, and 6 and
> output them to sockets. However writes to UARTs 2 and 3 just disappear. They
> don't even trigger my printf in stm32f2xx_usart_write. It seems like they
> are being intercepted somewhere, and unfortunately my knowledge of QEMU is
> too low to know where to look. Any pointers would be greatly appreciated.

Strange. There could be something else addressed there. If you run
'info mtree' at the QEMU prompt (Ctrl-a + c) you should be able to see
the memory map of the system.

Thanks,

Alistair

>
> Thanks again for all your help
>
> On Thu, Oct 6, 2016 at 8:18 PM, Alistair Francis <address@hidden>
> wrote:
>>
>> QEMU only supports the Netduino (not Netduino 2) it is possible that
>> the base addresses are different and that is why you aren't seeing the
>> serial output.
>>
>> Thanks,
>>
>> Alistair
>>
>>
>> On Wed, Oct 5, 2016 at 11:56 AM, Seth <address@hidden> wrote:
>> > Public bug reported:
>> >
>> > Writes to UART 2 and 3 disappear. As a sanity check I put printf
>> > statements in the function stm32f2xx_usart_write in
>> > qemu/hw/char/stm32f2xx_usart.c and recompiled qemu. The result confirmed
>> > text sent to UART1 and UART4 are sent to that function while text sent
>> > to UART 2 and 3 are not. I assume writes to all 4 need to make it to
>> > that function for emulations to operate correctly.
>> >
>> > Example code that writes to all 4 UARTs/USARTs (does not contain the
>> > printf statements mention above):
>> > https://github.com/skintigh/baremetal_netduino2
>> >
>> > ** Affects: qemu
>> >      Importance: Undecided
>> >          Status: New
>> >
>> > --
>> > You received this bug notification because you are a member of qemu-
>> > devel-ml, which is subscribed to QEMU.
>> > https://bugs.launchpad.net/bugs/1630723
>> >
>> > Title:
>> >   UART writes to netduino2/stm32f205-soc disappear
>> >
>> > Status in QEMU:
>> >   New
>> >
>> > Bug description:
>> >   Writes to UART 2 and 3 disappear. As a sanity check I put printf
>> >   statements in the function stm32f2xx_usart_write in
>> >   qemu/hw/char/stm32f2xx_usart.c and recompiled qemu. The result
>> >   confirmed text sent to UART1 and UART4 are sent to that function while
>> >   text sent to UART 2 and 3 are not. I assume writes to all 4 need to
>> >   make it to that function for emulations to operate correctly.
>> >
>> >   Example code that writes to all 4 UARTs/USARTs (does not contain the
>> > printf statements mention above):
>> >   https://github.com/skintigh/baremetal_netduino2
>> >
>> > To manage notifications about this bug go to:
>> > https://bugs.launchpad.net/qemu/+bug/1630723/+subscriptions
>> >
>
>