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Re: [Qemu-devel] [PATCH 1/2] hw/mips/jazz: create ESP device directly vi
Re: [Qemu-devel] [PATCH 1/2] hw/mips/jazz: create ESP device directly via qdev
Wed, 13 Jun 2018 16:12:04 +0200
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On 13/06/2018 15:06, Mark Cave-Ayland wrote:
>> Heh, those are disgusting indeed. :) So I guess it would have to stay,
>> only MIPS can use the pure MemoryRegion-based approach.
> The only option I can think of is inserting an AddressSpace between the
> esp/ledma device and the IOMMU AddressSpace which intercepts the DMA
> request (addr, len, direction).
> I can then grab a reference to the device from the MemoryRegion opaque,
> perform the magic, and then manually invoke address_space_rw() on iommu_as.
> Is there a hook somewhere in the memory API that could allow me to do this?
No, I don't think so. Only MMIO regions intercept reads/writes, and
they only do it at 1/2/4/8 byte granularity.
>> Regarding pcnet, is CSR_BSWP really a no-op on PCI cards? If not, an
>> option could be to move that handling to pcnet.c - making the ledma swap
>> unconditional and removing the do_bswap argument. The disadvantage is
>> that SPARC would swap twice, and you'd have to keep the callback because
>> of s->dmaregs, but maybe it's still worthwhile.
> Hmmm good question. If we can intercept the request above, that would be
> my preferred option as something tells it me it might be useful for
> other similar situations.
Yeah, it wouldn't be a great improvement, but there would be the benefit
of more accurate emulation.
Re: [Qemu-devel] [PATCH 0/2] scsi: remove legacy esp_init() function, Mark Cave-Ayland, 2018/06/27