[Qemu-devel] Why does qemu not support qemu-system-armeb?

[Qemu-devel] Why does qemu not support qemu-system-armeb?

[Ljun]

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Hello everyone,I am working on big endian for arm.I change the qemu configure and create a qemu-system-armeb,but I want to know qemu whether support armeb-softmmu. 

Software engineer ,Ljun

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Re: [Qemu-devel] Why does qemu not support qemu-system-armeb?

[Peter Maydell]

On 14 June 2014 14:49, Ljun <1275151072@qq.com> wrote:
> Hello everyone,I am working on big endian for arm.I change the qemu
> configure and create a qemu-system-armeb,but I want to know qemu whether
> support armeb-softmmu.

The answer to "why is there no qemu-system-armeb" is in two parts:

(1) We don't support big-endian system emulation. There would need
to be work done to implement this beyond just enabling an extra
configuration.

(2) If we did support big-endian system emulation, the right way
to implement this would be to keep it in qemu-system-arm, and
just have the CPU support the various control bits (SCTLR.B,
SCTLR.EE, CPSR.E, etc).

(3) We would need a model of some actual board which used
a CPU in big-endian mode. (These days if it's purely for a
virtual machine you could use the "virt" board, though.)

Are you interested in big-endian emulation:
 * in 64-bit (AArch64/ARM64) ?
 * in 32-bit v7 (what the ARM ARM calls "BE8") ?
 * old-fashioned ARMv5 style ("BE32") ?

thanks
-- PMM

Re: [Qemu-devel] Why does qemu not support qemu-system-armeb?

[Paolo Bonzini]

Il 15/06/2014 11:08, Peter Maydell ha scritto:
> On 14 June 2014 14:49, Ljun <1275151072@qq.com> wrote:
>> Hello everyone,I am working on big endian for arm.I change the qemu
>> configure and create a qemu-system-armeb,but I want to know qemu whether
>> support armeb-softmmu.
>
> The answer to "why is there no qemu-system-armeb" is in two parts:
>
> (1) We don't support big-endian system emulation. There would need
> to be work done to implement this beyond just enabling an extra
> configuration.
>
> (2) If we did support big-endian system emulation, the right way
> to implement this would be to keep it in qemu-system-arm, and
> just have the CPU support the various control bits (SCTLR.B,
> SCTLR.EE, CPSR.E, etc).

Also, I have redone my setend patches to support SCTLR.B too, but I have 
yet to submit them.  I have no idea how to test them. :)

Paolo

Re: [Qemu-devel] =?gb18030?b?u9i4tKO6UmU6IFdoeSBkb2VzIHFlbXUgbm90IHN1?= =?gb18030?q?pport_qemu-system-armeb=3F?=

[Paolo Bonzini]

Il 16/06/2014 15:17, Ljun ha scritto:
> I am very glad to you have finished the patch for qemu-system-armeb.I
> have seriously read your patch in 29 May about the armeb. I want to know
> two points:
> 1) whether combined your patch into the qemu , it can support
> qemu-system-armeb .Do I need to do otherthings?

Actually the binary will still be called qemu-system-arm, and should 
support both endiannesses.

> 2) whether you have a plan to verify the patch and submit it?

I plan to send it this week.  Help with testing will be welcome.

Paolo