Re: [RFC PATCH v2 2/4] target/ppc: Disable unused facilities in the e600 CPU

[Cédric Le Goater]

On 12/1/21 00:01, Fabiano Rosas wrote:
> The e600 CPU is a successor of the 7448 and like all the 7450s CPUs,
> it has an optional software TLB feature.
>
> We have determined that there is no OS software support for the 7450
> software TLB available these days. See the previous commit for more
> information.
>
> This patch disables the SPRs and instructions related to software TLB
> from the e600 CPU.
>
> No functional change intended. These facilities should be used by the
> OS in interrupt handlers for interrupts that QEMU never generates.
>
> Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

> ---
>   target/ppc/cpu_init.c | 6 +-----
>   1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
> index 509df35d09..962acf295f 100644
> --- a/target/ppc/cpu_init.c
> +++ b/target/ppc/cpu_init.c
> @@ -2537,9 +2537,6 @@ static void init_excp_7450(CPUPPCState *env)
>       env->excp_vectors[POWERPC_EXCP_TRACE]    = 0x00000D00;
>       env->excp_vectors[POWERPC_EXCP_PERFM]    = 0x00000F00;
>       env->excp_vectors[POWERPC_EXCP_VPU]      = 0x00000F20;
> -    env->excp_vectors[POWERPC_EXCP_IFTLB]    = 0x00001000;
> -    env->excp_vectors[POWERPC_EXCP_DLTLB]    = 0x00001100;
> -    env->excp_vectors[POWERPC_EXCP_DSTLB]    = 0x00001200;
>       env->excp_vectors[POWERPC_EXCP_IABR]     = 0x00001300;
>       env->excp_vectors[POWERPC_EXCP_SMI]      = 0x00001400;
>       env->excp_vectors[POWERPC_EXCP_VPUA]     = 0x00001600;
> @@ -6643,7 +6640,6 @@ static void init_proc_e600(CPUPPCState *env)
>       /* Memory management */
>       register_low_BATs(env);
>       register_high_BATs(env);
> -    register_74xx_soft_tlb(env, 128, 2);
>       init_excp_7450(env);
>       env->dcache_line_size = 32;
>       env->icache_line_size = 32;
> @@ -6667,7 +6663,7 @@ POWERPC_FAMILY(e600)(ObjectClass *oc, void *data)
>                          PPC_CACHE_DCBA | PPC_CACHE_DCBZ |
>                          PPC_MEM_SYNC | PPC_MEM_EIEIO |
>                          PPC_MEM_TLBIE | PPC_MEM_TLBSYNC |
> -                       PPC_MEM_TLBIA | PPC_74xx_TLB |
> +                       PPC_MEM_TLBIA |
>                          PPC_SEGMENT | PPC_EXTERN |
>                          PPC_ALTIVEC;
>       pcc->insns_flags2 = PPC_NONE;