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Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region
From: |
Pavel Fedin |
Subject: |
Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region |
Date: |
Mon, 27 Jul 2015 17:36:07 +0300 |
Hello!
> > + /* High MMIO space */
> > + mmio_alias = g_new0(MemoryRegion, 1);
> > + memory_region_init_alias(mmio_alias, OBJECT(dev), "pcie-mmio-high",
> > + mmio_reg, base_mmio_high, size_mmio_high);
> > + memory_region_add_subregion(get_system_memory(), base_mmio_high,
> > mmio_alias);
> Is there any specific reason to have 2 separate regions vs using 1 like in
> pc_pci_as_mapping_init()
> using region priority instead of splitting.
Unfortunately i'm not familiar very well with qemu memory internals. I saw PC
code and i know that
it adds PCI region of the size of the whole memory, then adds other things as
overlapped regions.
But wouldn't it be some resource waste in this case? I understand that in PC
absolutely all "unused"
addresses fall through to PCI, so that any device can plug in there. On ARM
this is different, PCI
controller is not a core of the system, it's just one of devices instead. And
on our case a huge
part of PCI region between VIRT_PCIE_MMIO and VIRT_PCIE_MMIO_HIGH would never
be used. Does it worth
that ?
Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia
- [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Pavel Fedin, 2015/07/27
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Igor Mammedov, 2015/07/27
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region,
Pavel Fedin <=
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Pavel Fedin, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Peter Maydell, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Pavel Fedin, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Peter Maydell, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Pavel Fedin, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Peter Maydell, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Pavel Fedin, 2015/07/29
- Re: [Qemu-devel] [PATCH v3] hw/arm/virt: Add high MMIO PCI region, Igor Mammedov, 2015/07/29