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Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes |
Date: |
Mon, 16 Aug 2021 12:58:14 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 |
On 8/16/21 12:26 PM, Peter Maydell wrote:
> On Mon, 16 Aug 2021 at 06:46, David Gibson <david@gibson.dropbear.id.au>
> wrote:
>>
>> On Sun, Aug 15, 2021 at 07:59:15PM -0700, Guenter Roeck wrote:
>>> IBM EMAC Ethernet controllers are not emulated by qemu. If they are
>>> enabled in devicetree files, they are instantiated in Linux but
>>> obviously won't work. Disable associated devicetree nodes to prevent
>>> unpredictable behavior.
>>>
>>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>>
>> I'll wait for Zoltan's opinion on this, but this sort of thing is why
>> I was always pretty dubious about qemu *loading* a dtb file, rather
>> than generating a dt internally.
>
> My take is that if you have to modify the dtb file to get QEMU to
> work, then that's a bug in QEMU that should be fixed. It's no
> worse than for the machines we have that don't use dtb and where
> the kernel just knows what the hardware is. (In my experience
> Arm kernels can be a bit finicky about wanting the right dtb
> and not some earlier or later one, so I think at least for Arm
> trying to generate a dt for our non-virt boards would have been
> pretty painful and liable to "new kernels don't boot any more" bugs.)
>
> Is it sufficient to create stub "unimplemented-device" ethernet
> controllers here, or does the guest want more behaviour than that?
For raspi4 "unimplemented-device" is not enough, so what would
be the ideal resolution for "the guest wants more behaviour"
when we don't have time / interest / specs for the missing
pieces?
- [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Guenter Roeck, 2021/08/15
- Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Peter Maydell, 2021/08/16
- Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Guenter Roeck, 2021/08/16
- Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Peter Maydell, 2021/08/16
- Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Guenter Roeck, 2021/08/16
- Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Peter Maydell, 2021/08/16
- Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes, Guenter Roeck, 2021/08/16