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Subject: Re: [PATCH 3/4] powerpc/powernv: Enable TM without suspend if possible
To: Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@ozlabs.org
Cc: stewart@linux.vnet.ibm.com, mikey@neuling.org, cyrilbur@gmail.com
References: <1507803439-12862-1-git-send-email-mpe@ellerman.id.au>
 <1507803439-12862-3-git-send-email-mpe@ellerman.id.au>
From: Florian Weimer <fweimer@redhat.com>
Message-ID: <920a68e7-1bb5-3ace-2aaf-1594d8845721@redhat.com>
Date: Thu, 19 Oct 2017 12:07:10 +0200
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On 10/12/2017 12:17 PM, Michael Ellerman wrote:
> +	pr_info("Enabling TM (Transactional Memory) with Suspend Disabled\n");
> +	cur_cpu_spec->cpu_features |= CPU_FTR_TM;
> +	cur_cpu_spec->cpu_user_features2 |= PPC_FEATURE2_HTM_NO_SUSPEND;
> +	tm_suspend_disabled = true;

This doesn't look right because if suspend is not available, you need to 
clear the original PPC_FEATURE2_HTM flag because the semantics are not 
right, so that applications can use fallback code.  Otherwise, 
applications may incorrectly select the HTM code and break if running on 
a system which supports HTM, but without the suspend state.

The new flag should say that HTM is supported, but without the suspend 
state, and it should be always set if PPC_FEATURE2_HTM is set.

Thanks,
Florian