linux-kernel - Re: [PATCH v1 0/4] Enable PEBS when only have PEBS via PT w/o DS

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Message-ID: <87h835edqn.fsf@ashishki-desk.ger.corp.intel.com>
Date:   Fri, 15 Nov 2019 10:38:08 +0200
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Luwei Kang <luwei.kang@...el.com>, kvm-pmu@...ists.intel.com
Cc:     ak@...ux.intel.com, kan.liang@...ux.intel.com,
        Luwei Kang <luwei.kang@...el.com>, peterz@...radead.org,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH v1 0/4] Enable PEBS when only have PEBS via PT w/o DS

You forgot to CC Peter and LKML.

Luwei Kang <luwei.kang@...el.com> writes:

> This patchset is purely perf event system changes that to enable the
> PEBS when the system only supports PEBS via Intel PT w/o DS. Currently,
> there don't have such hardware which only supports PEBS via PT w/o DS
> but it is possible in KVM guest. In Tremont Atom platforms, PEBS via
> PT is the only way to enabled PEBS in KVM guest.

I don't understand what this says. If PEBS-via-PT is available and DS is
not available, what happens and why?

Regards,
--
Alex