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Re: [Qemu-devel] [PATCH qemu] isa-bus: Replace assert() about DMA with e
From: |
John Snow |
Subject: |
Re: [Qemu-devel] [PATCH qemu] isa-bus: Replace assert() about DMA with error report |
Date: |
Mon, 6 Nov 2017 19:49:31 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
On 10/26/2017 04:00 AM, Alexey Kardashevskiy wrote:
> Running "qemu-system-ppc64 -machine prep -device i82374" creates an ISA
> bus with two i82374 DMA controllers - one is implicit from ppc_prep_init(),
> the other one is from "-device i82374". QEMU asserts but it is not
> immediately clear why.
>
> This adds an error message to explain the failure.
>
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
>
>
> Better phase suggestions are welcome. Thanks!
>
>
> ---
> hw/isa/isa-bus.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/hw/isa/isa-bus.c b/hw/isa/isa-bus.c
> index 348e0eab9d..553707b18d 100644
> --- a/hw/isa/isa-bus.c
> +++ b/hw/isa/isa-bus.c
> @@ -107,7 +107,10 @@ void isa_connect_gpio_out(ISADevice *isadev, int
> gpioirq, int isairq)
> void isa_bus_dma(ISABus *bus, IsaDma *dma8, IsaDma *dma16)
> {
> assert(bus && dma8 && dma16);
> - assert(!bus->dma[0] && !bus->dma[1]);
> + if (bus->dma[0] || bus->dma[1]) {
> + error_setg(&error_fatal,
> + "DMA is already set to ISA bus, duplicated DMA
> controller?");
> + }
> bus->dma[0] = dma8;
> bus->dma[1] = dma16;
> }
>
I suppose it's an improvement strictly, but really we're just naming a
runtime assertion here. We should be avoiding the assertion -- and then
how valuable is the error message?
Is this something we anticipate can never be fixed? (I.e. exclusively
the cause of asking for impossible configurations?)