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Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instr
From: |
Nikunj A Dadhania |
Subject: |
Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction |
Date: |
Tue, 09 Aug 2016 14:47:46 +0530 |
User-agent: |
Notmuch/0.21 (https://notmuchmail.org) Emacs/25.0.94.1 (x86_64-redhat-linux-gnu) |
Nikunj A Dadhania <address@hidden> writes:
> David Gibson <address@hidden> writes:
>
>> [ Unknown signature status ]
>> On Mon, Aug 08, 2016 at 07:33:37AM +1000, Benjamin Herrenschmidt wrote:
>>> On Sun, 2016-08-07 at 23:06 +0530, Nikunj A Dadhania wrote:
>>> > +target_ulong helper_darn(uint32_t l)
>>> > +{
>>> > + target_ulong r = UINT64_MAX;
>>> > +
>>> > + if (l <= 2) {
>>> > + do {
>>> > + r = random() * random();
>>> > + r &= l ? UINT64_MAX : UINT32_MAX;
>>> > + } while (r == UINT64_MAX);
>>> > + }
>>> > +
>>> > + return r;
>>> > +}
>>> > #endif
>>>
>>> Isn't this a bit week ? Look at the implementation of H_RANDOM...
>>
>> Indeed, you should be using the rng backend that H_RANDOM, virtio-rng
>> and the Intel random number instruction all use.
Can you point me to the intel instruction, I couldn't get rdrand
implementation.
> I was looking at implementing this, AFAIU, I have to get a new RNG
> object in the initialization routine. We would need an instance of this
> per machine. So for pseries I can add in ppc_spapr_init(). I am not sure
> in case of linux-user where should this be initialized.
>
> One other place was init_proc_POWER9(), but that will be per cpu and
> member of CPUPPCState structure. Advantage is it will work for system
> emulation and linux-user both and we would not need a lock.
More issues here. Random backend is not compiled for linux-user, adding
that wasn't difficult, but then rng_backend_request_entropy() uses
qemu_set_fd_handler() which is a stub for linux-user
(stubs/set-fd-handler.c)
Regards,
Nikunj
- [Qemu-devel] [PATCH 1/6] target-ppc: add xxspltib instruction, (continued)
- [Qemu-devel] [PATCH 1/6] target-ppc: add xxspltib instruction, Nikunj A Dadhania, 2016/08/07
- [Qemu-devel] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/07
- Re: [Qemu-devel] [PATCH 2/6] target-ppc: Implement darn instruction, David Gibson, 2016/08/08
- Re: [Qemu-devel] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/09
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction,
Nikunj A Dadhania <=
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, David Gibson, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/12
- Message not available
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Thomas Huth, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Thomas Huth, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Thomas Huth, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Nikunj A Dadhania, 2016/08/12
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/6] target-ppc: Implement darn instruction, Richard Henderson, 2016/08/12