Re: [Bug 1880355] [NEW] Length restrictions for fw_cfg_dma_transfer?

[Philippe Mathieu-Daudé]

On 5/24/20 3:40 PM, Peter Maydell wrote:
> On Sun, 24 May 2020 at 11:30, Philippe Mathieu-Daudé <address@hidden> wrote:
>> It looks to me a normal behavior for a DMA device. DMA devices have a
>> different address space view than the CPUs.
>> Also note the fw_cfg is a generic device, not restricted to the x86 arch.
> 
> In an ideal world all our DMA devices would use some kind of common
> framework or design pattern so they didn't hog all the CPU
> and/or spend minutes with the BQL held if the guest requests
> an enormous-sized DMA. In practice many of them just have
> a simple "loop until the DMA transfer is complete" implementation...

Is this framework already implemented in the hidden dma-helpers.c?

Apparently this file was written for BlockBackend, but the code seems
rather generic.