Re: [Qemu-devel] [Bug 1637974] [NEW] dead code in pl080 functions

[Peter Maydell]

On 31 October 2016 at 10:48, jeyyej <address@hidden> wrote:
> Public bug reported:
>
> pl080 is arm dma controller virtual device.
> source code path: hw/dma/pl080.c
> I find there are two same dead code in pl080_read and pl080_write,

> + if this DEADCODE is not the author's original purpose,
> + Then there must be something in logic goes wrong, pl080 have NEVER works 
> correctly ?

Yes, this code is incorrect. However the only registers
affected are those that set up the DMA channels, and
the code for actually doing DMA transfers will assert if
the guest ever tries to use it (see the hw_error() call in
pl080_run()), so even if the guest could set up the DMA
channels it would run into problems later.

This device is only used in the versatilepb board, and
I don't think Linux attempts to use it for DMA, so nobody's
ever needed to care that it's actually totally broken
for anything beyond "shouldn't crash the kernel when it
tries to probe for and initialize it".

thanks
-- PMM