A question about KVM_SET_MEMORY_REGION ioctl

A question about KVM_SET_MEMORY_REGION ioctl

[Zhang, Xiantao]

Currently, KVM_SET_MEMORY_REGION ioctl is put under arch, but its
implementation is in common code . From code logic, it seems very
strange.  Maybe I missed some threads about its discuss, who can tell me
the story ? Thanks a lot! :)
Xiantao

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Re: A question about KVM_SET_MEMORY_REGION ioctl

[Izik Eidus]

On Thu, 2007-11-15 at 23:21 +0800, Zhang, Xiantao wrote:
> Currently, KVM_SET_MEMORY_REGION ioctl is put under arch, but its
> implementation is in common code . From code logic, it seems very
> strange.  Maybe I missed some threads about its discuss, who can tell me
> the story ? Thanks a lot! :)
> Xiantao

kvm x86 have 2 ways to create memory
one old way:
allocate the memory inside the kernel
one new way:
allocate the memory inside userspace and send a address to the kernel 

the ioctl that call to allocate memory inside the kernel is:
KVM_SET_MEMORY_REGION
and the one that allocate the memory in userspace is:
KVM_SET_USER_MEMORY_REGION

all the ports of kvm to other architactures will use the
KVM_SET_USER_MEMORY_REGION, and KVM_SET_MEMORY_REGION is left just for
legacy support for older userspace

(checkout KVM_SET_USER_MEMORY_REGION, it is in the common code)


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Re: A question about KVM_SET_MEMORY_REGION ioctl

[Zhang, Xiantao]

Izik Eidus wrote:
> On Thu, 2007-11-15 at 23:21 +0800, Zhang, Xiantao wrote:
>> Currently, KVM_SET_MEMORY_REGION ioctl is put under arch, but its
>> implementation is in common code . From code logic, it seems very
>> strange.  Maybe I missed some threads about its discuss, who can
>> tell me the story ? Thanks a lot! :) Xiantao
> 
> kvm x86 have 2 ways to create memory
> one old way:
> allocate the memory inside the kernel
> one new way:
> allocate the memory inside userspace and send a address to the kernel
> 
> the ioctl that call to allocate memory inside the kernel is:
> KVM_SET_MEMORY_REGION
> and the one that allocate the memory in userspace is:
> KVM_SET_USER_MEMORY_REGION
> 
> all the ports of kvm to other architactures will use the
> KVM_SET_USER_MEMORY_REGION, and KVM_SET_MEMORY_REGION is left just for
> legacy support for older userspace
> 
> (checkout KVM_SET_USER_MEMORY_REGION, it is in the common code)

Thank you. Izik!    But the name of kvm_vm_ioctl_set_memory_region is
confusing. Maybe we should change it to 
kvm_vm_ioctl_set_user_memory_region :-)
Xiantao

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Re: A question about KVM_SET_MEMORY_REGION ioctl

[Avi Kivity]

Zhang, Xiantao wrote:
> Currently, KVM_SET_MEMORY_REGION ioctl is put under arch, but its
> implementation is in common code . From code logic, it seems very
> strange.  Maybe I missed some threads about its discuss, who can tell me
> the story ? Thanks a lot! :)
>   

KVM_SET_MEMORY_REGION is obsolete and only maintained for backwards 
compatibility.  KVM_SET_USER_MEMORY_REGION should be used instead.


-- 
error compiling committee.c: too many arguments to function


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