Re: linux-next: manual merge of the kvm-ppc tree with the powerpc-merge tree

On 10/11/2012 10:56:51 AM, Alexander Graf wrote:

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On 11.10.2012, at 17:50, Scott Wood wrote:
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On 10/11/2012 08:04:58 AM, Alexander Graf wrote:

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On 11.10.2012, at 05:32, Tabi Timur-B04825 wrote:

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On Wed, Oct 10, 2012 at 9:47 PM, Stephen Rothwell =20

[off-list ref] wrote:

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Commit 549d62d889b4 ("KVM: PPC: use definitions in epapr header
for hcalls") from the kvm-ppc tree added an include of =20

asm/epapr_hcall.h

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to the user visible part of asm/kvm_para.h so asm/epapr_hcall.h =20

became a

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user visible header file.

Any real user-space code that tries to call any of the functions =20

in

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epapr_hcall.h will cause an exception.

Actually it'll cause a linker error, as of the "Don't use hardcoded =20

opcode for ePAPR hcall invocation" patch.

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Claiming that kernel header files that KVM needs are suddenly
user-space header files doesn't make much sense to me, but I =20

guess

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it's not my decision.

This is about kvm_host.h, which is the part that is exported to =20

user space. It usually contains constants and structs that are =20
required for the API.

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s/kvm_host/kvm_para/

I'm not sure anything in kvm_para.h or epapr_hcalls.h would be of =20

use to userspace, but it would be of use to the guest OS, so it's =20
still not kernel-internal.

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The variable externs should be #ifdef __KERNEL__ as David points =20

out.  The asm stuff could still be useful in a guest OS if the guest =20
provides epapr_hypercall_start.
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I don't think we should worry about guest kernel code potentially =20
having use for this. Let's make the user space headers be great for =20
user space usage, not for guest code usage :).

Well, that asm stuff started out as a guest header (from Freescale's =20
Topaz hypervisor), not a Linux header. :-)

-Scott=