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Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine
From: |
Stafford Horne |
Subject: |
Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine |
Date: |
Tue, 7 Jun 2022 21:12:07 +0900 |
On Tue, Jun 07, 2022 at 11:43:08AM +0100, Peter Maydell wrote:
> So I don't have a strong view on whether these devices should
> be DEVICE_NATIVE_ENDIAN or DEVICE_LITTLE_ENDIAN (except that
> my impression is that a DEVICE_LITTLE_ENDIAN device on a
> big-endian system is a bit weird, because it means the guest
> has to byteswap everything. You see that with PCI devices because
> the PCI spec mandates LE, but not often elsewhere).
>
> If there's an official-ish spec for how goldfish devices are
> supposed to behave (does anybody have a pointer to one?) and it says
> "always little-endian" then that would probably suggest that fixing
> m68k would be nice if we can.
I think there are some conflicting thoughts on this.
In Geert's he mentioned:
Using Goldfish devices as little-endian devices should be fine.
In Arnd's mail he mentions:
https://lore.kernel.org/lkml/CAK8P3a1oN8NrUjkh2X8jHQbyz42Xo6GSa=5n0gD6vQcXRjmq1Q@mail.gmail.com/#t
... the device was clearly defined as having little-endian
registers,
Based on that I was thinking that switching to DEVICE_LITTLE_ENDIAN would make
sense.
However, in a followup mail from Laurent we see:
https://lore.kernel.org/lkml/cb884368-0226-e913-80d2-62d2b7b2e761@vivier.eu/
The reference document[1] doesn't define the endianness of goldfish.
[1]
https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
The documentation does not clearly specify it. So maybe maybe or1k should just
be updated on the linux side and add gf_ioread32/gf_iowrite32 big-endian
accessors.
-Stafford
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, (continued)
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Geert Uytterhoeven, 2022/06/03
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Stafford Horne, 2022/06/04
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Stafford Horne, 2022/06/05
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Jason A. Donenfeld, 2022/06/05
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Jason A. Donenfeld, 2022/06/07
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Geert Uytterhoeven, 2022/06/07
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Arnd Bergmann, 2022/06/07
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Stafford Horne, 2022/06/07
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Arnd Bergmann, 2022/06/07
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Peter Maydell, 2022/06/07
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine,
Stafford Horne <=
- Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Arnd Bergmann, 2022/06/07
Re: [RFC PATCH 3/3] hw/openrisc: Add the OpenRISC virtual machine, Stafford Horne, 2022/06/04