Re: [Qemu-devel] [RFC] Virt machine memory map

[Peter Maydell]

On 20 July 2015 at 09:55, Pavel Fedin <address@hidden> wrote:
>  Hello!
>
>  In our project we work on a very fast paravirtualized network I/O drivers, 
> based  on ivshmem. We
> successfully got ivshmem working on ARM, however with one hack.
> Currently we have:
> --- cut ---
>     [VIRT_PCIE_MMIO] =          { 0x10000000, 0x2eff0000 },
>     [VIRT_PCIE_PIO] =           { 0x3eff0000, 0x00010000 },
>     [VIRT_PCIE_ECAM] =          { 0x3f000000, 0x01000000 },
>     [VIRT_MEM] =                { 0x40000000, 30ULL * 1024 * 1024 * 1024 },
> --- cut ---
>  And MMIO region is not enough for us because we want to have 1GB mapping for 
> PCI device. In order
> to make it working, we modify the map as follows:
> --- cut ---
>     [VIRT_PCIE_MMIO] =            { 0x10000000, 0x7eff0000 },
>     [VIRT_PCIE_PIO] =           { 0x8eff0000, 0x00010000 },
>     [VIRT_PCIE_ECAM] =          { 0x8f000000, 0x01000000 },
>     [VIRT_MEM] =             { 0x90000000, 30ULL * 1024 * 1024 * 1024 },
> --- cut ---
>  The question is - how could we upstream this? I believe modifying 32-bit 
> virt memory map this way
> is not good. Will it be OK to have different memory map for 64-bit virt ?

I think the theory we discussed at the time of putting in the PCIe
device was that if we wanted this we'd add support for the other
PCIe memory window (which would then live at somewhere above 4GB).
Alex, can you remember what the idea was?

But to be honest I think we weren't expecting anybody to need
1GB of PCI MMIO space unless it was a video card...

thanks
-- PMM