Hi Andreas,
We're trying to eliminate the memory operations of the HDLCD controller.
I believe that the way it is currently structured is:
- Kernel writes the pixel data to a predefined memory region
- Gem5 HDLCD controller copies this data via DMA to its internal buffer
- Gem5 HDLCD controller displays the pixels
Don't modern GPUs skip the double-copy and just get the kernel to copy once
onto the hardware buffer?
Either way, for some validation at our end, we would like to remove all
timer based operations. To achieve this, we would have to eliminate the
simulated reads/writes caused by the HDLCD (which is periodic).
This is what we're trying to achieve. Once I understand how to translate
addresses, my plan is to just issue a memcpy instead of doing the DMA
operations.
Regards
Guru
On Thu, Jun 11, 2015 at 3:59 PM, Andreas Hansson <[email protected]>
wrote:
> Hi Guru,
>
> You seem to be talking about two different issues:
>
> 1. Copy from physical address in the guest to the host.
> 2. Copy “behind the back” of the guest from physical address A to
> physical address B.
>
> What is it you are trying to accomplish? Also, if you are going down the
> path of (2), take care not to confuse the guest by writing over something
> that’s actually used.
>
> Andreas
>
> From: Guru Prasad <[email protected]>
> Reply-To: gem5 users mailing list <[email protected]>
> Date: Thursday, 11 June 2015 16:11
> To: gem5 users mailing list <[email protected]>
> Subject: Re: [gem5-users] Copy memory out of simulation
>
> Hi Andreas,
>
> Thanks for your response. I'm trying to do this in the hdlcd code.
> In src/dev/arm/hdlcd.cc, instead of the call to dmaAction, I want to
> copy the memory from the source to the destination without simulating any
> of the reads/writes.
>
> Could you point me to an example of PortProxy implementation? Like I
> mentioned earlier, I tried using the fs_translating_port_proxy functions
> which didn't work out.
>
> Regards
> Guru
>
>
> On Wed, Jun 10, 2015 at 3:37 AM, Andreas Hansson <[email protected]>
> wrote:
>
>> Hi Guru,
>>
>> If you are talking about guest physical address, then it should be very
>> easy, as it is a linear mapping to the host. The KVM CPU uses this fact
>> quite extensively. Depending on where you want to do this, the easiest may
>> be to create a PortProxy and simply read it out.
>>
>> Andreas
>>
>> From: Guru Prasad <[email protected]>
>> Reply-To: gem5 users mailing list <[email protected]>
>> Date: Tuesday, 9 June 2015 23:36
>> To: gem5 users mailing list <[email protected]>
>> Subject: [gem5-users] Copy memory out of simulation
>>
>> Hi,
>>
>> I'm trying to copy out a chunk of memory from within the simulation.
>> Is there a way to translate simulation memory addresses to host
>> addresses?
>>
>> I've looked at CopyOut, however, I don't have access to the current
>> ThreadContext.
>> When I tried with sys->getThreadContext(0), I got:
>> panic: Table walkers support functional accesses. We should never get here
>>
>>
>> Regards
>> Guru
>>
>>
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> recipient, please notify the sender immediately and do not disclose the
> contents to any other person, use it for any purpose, or store or copy the
> information in any medium. Thank you.
>
> ARM Limited, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ,
> Registered in England & Wales, Company No: 2557590
> ARM Holdings plc, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ,
> Registered in England & Wales, Company No: 2548782
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