Subject: Re: [RFC PATCH 10/10] PPC: BOOK3S: Disable/Enable TM looking at the ibm,pa-features device tree entry

From: Alexander Graf <[email-masked]>
Date: Wed, 29 Jan 2014 18:37:17 +0100

On 01/28/2014 05:44 PM, Aneesh Kumar K.V wrote:
> Runtime disable transactional memory feature looking at pa-features
> device tree entry. We need to do this so that we can run a kernel
> built with TM config in PR mode. For PR guest we provide a device
> tree entry with TM feature disabled in pa-features
>
> Signed-off-by: Aneesh Kumar K.V <[email-masked]>

We need to be able to run kernels without this patch, so better fix TM 
for good - worst case by always aborting transactions.

Alex

> ---
>   arch/powerpc/kernel/prom.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index fa0ad8aafbcc..de8c2caf1024 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -160,6 +160,11 @@ static struct ibm_pa_feature {
>   	{CPU_FTR_NODSISRALIGN, 0, 0,	1, 1, 1},
>   	{0, MMU_FTR_CI_LARGE_PAGE, 0,	1, 2, 0},
>   	{CPU_FTR_REAL_LE, PPC_FEATURE_TRUE_LE, 5, 0, 0},
> +	/*
> +	 * We should use CPU_FTR_TM_COMP so that if we disable TM, it won't get
> +	 * enabled via device tree
> +	 */
> +	{CPU_FTR_TM_COMP, 0, 0,		22, 0, 0},
>   };
>   
>   static void __init scan_features(unsigned long node, unsigned char *ftrs,