From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
To: Nicholas Piggin <npiggin@gmail.com>,
Pratik Rajesh Sampat <psampat@linux.ibm.com>
Cc: ego@linux.vnet.ibm.com, mikey@neuling.org,
pratik.r.sampat@gmail.com, linux-kernel@vger.kernel.org,
paulus@samba.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0, DAWRX0 for P10
Date: Mon, 20 Jul 2020 10:00:56 +0530 [thread overview]
Message-ID: <ddf13184-86a3-5b84-6b4f-d901fc884ba5@linux.ibm.com> (raw)
In-Reply-To: <1594619458.45vrahx59w.astroid@bobo.none>
Hi Nick,
On 7/13/20 11:22 AM, Nicholas Piggin wrote:
> Excerpts from Pratik Rajesh Sampat's message of July 10, 2020 3:22 pm:
>> Additional registers DAWR0, DAWRX0 may be lost on Power 10 for
>> stop levels < 4.
>> Therefore save the values of these SPRs before entering a "stop"
>> state and restore their values on wakeup.
>
> Hmm, where do you get this from? Documentation I see says DAWR is lost
> on POWER9 but not P10.
>
> Does idle thread even need to save DAWR, or does it get switched when
> going to a thread that has a watchpoint set?
I don't know how idle states works internally but IIUC, we need to save/restore
DAWRs. This is needed when user creates per-cpu watchpoint event.
Ravi
next prev parent reply other threads:[~2020-07-20 4:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 5:22 [PATCH v2 0/3] Power10 basic energy management Pratik Rajesh Sampat
2020-07-10 5:22 ` [PATCH v2 1/3] powerpc/powernv/idle: Exclude mfspr on HID1, 4, 5 on P9 and above Pratik Rajesh Sampat
2020-07-13 5:53 ` Nicholas Piggin
2020-07-10 5:22 ` [PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0, DAWRX0 for P10 Pratik Rajesh Sampat
2020-07-13 5:52 ` Nicholas Piggin
2020-07-20 4:30 ` Ravi Bangoria [this message]
2020-07-20 4:24 ` [PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0,DAWRX0 " Ravi Bangoria
2020-07-24 1:25 ` Michael Neuling
2020-07-24 6:34 ` Pratik Sampat
2020-07-10 5:22 ` [PATCH v2 3/3] powerpc/powernv/idle: Rename pnv_first_spr_loss_level variable Pratik Rajesh Sampat
2020-07-13 5:23 ` [PATCH v2 0/3] Power10 basic energy management Nicholas Piggin
2020-07-13 10:02 ` Pratik Sampat
2020-07-13 16:50 ` Nicholas Piggin
2020-07-13 18:27 ` Pratik Sampat
2020-07-13 10:48 ` Gautham R Shenoy
2020-07-13 16:58 ` Nicholas Piggin
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