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From: Thomas Huth <thuth@redhat.com>
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Date: Thu, 28 Jan 2016 16:45:21 +0100
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Subject: Re: [Qemu-devel] [PATCHv2 06/10] target-ppc: Remove unused mmu
 models from ppc_tlb_invalidate_one
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To: David Gibson <david@gibson.dropbear.id.au>, benh@kernel.crashing.org
Cc: aik@ozlabs.ru, lvivier@redhat.com, qemu-ppc@nongnu.org, agraf@suse.de, qemu-devel@nongnu.org

On 27.01.2016 11:13, David Gibson wrote:
> ppc_tlb_invalidate_one() has a big switch handling many different MMU
> types.  However, most of those branches can never be reached:
> 
> It is called from 3 places: from remove_hpte() and h_protect() in
> spapr_hcall.c (which always has a 64-bit hash MMU type), and from
> helper_tlbie() in mmu_helper.c.
> 
> Calls to helper_tlbie() are generated from gen_tlbiel, gen_tlbiel and
> gen_tlbiva.  The first two are only used with the PPC_MEM_TLBIE flag,
> set only with 32-bit or 64-bit hash MMU models, and gen_tlbiva() is
> used only on 440 and 460 models with the BookE mmu model.
> 
> These means the exhaustive list of MMU types which may call
> ppc_tlb_invalidate_one() is: POWERPC_MMU_SOFT_6xx, POWERPC_MMU_601,
> POWERPC_MMU_32B, POWERPC_MMU_SOFT_74xx, POWERPC_MMU_64B, POWERPC_MMU_2_03,
> POWERPC_MMU_2_06, POWERPC_MMU_2_07 and POWERPC_MMU_BOOKE.
> 
> Clean up by removing logic for all other MMU types from
> ppc_tlb_invalidate_one().
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
...
> @@ -2031,9 +2016,8 @@ void ppc_tlb_invalidate_one(CPUPPCState *env, target_ulong addr)
>          break;
>  #endif /* defined(TARGET_PPC64) */
>      default:
> -        /* XXX: TODO */
> -        cpu_abort(CPU(cpu), "Unknown MMU model\n");
> -        break;
> +        /* Should never reach here with other MMU models */
> +        assert(0);
>      }

May I suggest to simply use "abort()" instead of "assert(0)" ?

 Thomas