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Re: [PATCH 0/8] Simplify memory_region_add_subregion_overlap(..., priori
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From: |
Michael S. Tsirkin |
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Subject: |
Re: [PATCH 0/8] Simplify memory_region_add_subregion_overlap(..., priority=0) |
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Date: |
Sun, 15 Dec 2019 04:51:42 -0500 |
On Sat, Dec 14, 2019 at 04:28:08PM +0000, Peter Maydell wrote:
> (It doesn't actually assert that it doesn't
> overlap because we have some legacy uses, notably
> in the x86 PC machines, which do overlap without using
> the right function, which we've never tried to tidy up.)
It's not exactly legacy uses.
To be more exact, the way the non overlap versions
are *used* is to mean "I don't care what happens when they overlap"
as opposed to "will never overlap".
There are lots of regions where guest can make things overlapping
but doesn't, e.g. PCI BARs can be programmed to overlap
almost anything.
What happens on real hardware if you then access one of
the BARs is undefined, but programming itself is harmless.
That's why we can't assert.
--
MST
- [PATCH 3/8] hw/arm/xlnx-versal: Use memory_region_add_subregion() when priority is 0, (continued)
- [PATCH 3/8] hw/arm/xlnx-versal: Use memory_region_add_subregion() when priority is 0, Philippe Mathieu-Daudé, 2019/12/14
- [PATCH 2/8] hw/arm/raspi: Use memory_region_add_subregion() when priority is 0, Philippe Mathieu-Daudé, 2019/12/14
- [PATCH 6/8] hw/vfio/pci: Use memory_region_add_subregion() when priority is 0, Philippe Mathieu-Daudé, 2019/12/14
- [PATCH 5/8] hw/mips/boston: Use memory_region_add_subregion() when priority is 0, Philippe Mathieu-Daudé, 2019/12/14
- [PATCH 7/8] target/i386: Use memory_region_add_subregion() when priority is 0, Philippe Mathieu-Daudé, 2019/12/14
- [PATCH 4/8] hw/i386/intel_iommu: Use memory_region_add_subregion when priority is 0, Philippe Mathieu-Daudé, 2019/12/14
- Re: [PATCH 0/8] Simplify memory_region_add_subregion_overlap(..., priority=0), Peter Maydell, 2019/12/14
- Re: [PATCH 0/8] Simplify memory_region_add_subregion_overlap(..., priority=0),
Michael S. Tsirkin <=