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Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inpu
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate |
Date: |
Mon, 21 May 2018 16:02:49 +0100 |
On 21 May 2018 at 15:34, Paolo Bonzini <address@hidden> wrote:
> Why do the levels have to be migrated at all? It should be enough if
> the IRQ level is either migrated manually, or restored (e.g. in
> post_save callbacks) through other data that is migrated.
This is standard behaviour for devices: they track their
inbound irq/gpio lines, and then that becomes internal state for
them that must be migrated.
If we didn't migrate the input line state, then after a migration
the levels[] array would be all zeroes, and the next time a
connected device signalled a high-to-low transition we'd take
the output line low even if it should not be (because we'd have
forgotten that some other input lines were high).
In a different world, the state would be in the qemu_irq line itself
(in the same way that in hardware signal lines are their own state),
but we can't get there from here.
thanks
-- PMM
- Re: [Qemu-devel] [PATCH 14/27] iommu: Add IOMMU index concept to IOMMU API, (continued)
Re: [Qemu-devel] [PATCH 14/27] iommu: Add IOMMU index concept to IOMMU API, Richard Henderson, 2018/05/22
[Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Peter Maydell, 2018/05/21
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Paolo Bonzini, 2018/05/21
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Paolo Bonzini, 2018/05/30
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Peter Maydell, 2018/05/30
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Paolo Bonzini, 2018/05/31
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Peter Maydell, 2018/05/31
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Paolo Bonzini, 2018/05/31
- Re: [Qemu-devel] [PATCH 23/27] hw/core/or-irq: Support more than 16 inputs to an OR gate, Peter Maydell, 2018/05/31
[Qemu-devel] [PATCH 26/27] hw/arm/iotkit: Wire up MPC interrupt lines, Peter Maydell, 2018/05/21
[Qemu-devel] [PATCH 25/27] hw/arm/iotkit: Instantiate MPC, Peter Maydell, 2018/05/21