linux-kernel - RE: About add an A64FX cache control function into resctrl

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Date:   Thu, 29 Apr 2021 17:50:20 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     "Chatre, Reinette" <reinette.chatre@...el.com>,
        "tan.shaopeng@...itsu.com" <tan.shaopeng@...itsu.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>
CC:     "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        "'linux-arm-kernel@...ts.infradead.org'" 
        <linux-arm-kernel@...ts.infradead.org>,
        'James Morse' <james.morse@....com>,
        "misono.tomohiro@...itsu.com" <misono.tomohiro@...itsu.com>
Subject: RE: About add an A64FX cache control function into resctrl

>>>> [Sector cache function]
>>>> The sector cache function split cache into multiple sectors and
>>>> control them separately. It is implemented on the L1D cache and
>>>> L2 cache in the A64FX processor and can be controlled individually
>>>> for L1D cache and L2 cache. A64FX has no L3 cache. Each L1D cache and
>>>> L2 cache has 4 sectors. Which L1D sector is used is specified by the
>>>> value of [57:56] bits of address, how many ways of sector are
>>>> specified by the value of register (IMP_SCCR_L1_EL0).
>>>> Which L2 sector is used is specified by the value of [56] bits of
>>>> address, and how many ways of sector are specified by value of
>>>> register (IMP_SCCR_ASSIGN_EL1, IMP_SCCR_SET0_L2_EL1,
>>>> IMP_SCCR_SET1_L2_EL1).

Are A64FX binaries position independent?  I.e. could the OS reassign
a running task to a different sector by remapping it to different virtual
addresses during a context switch?

Or is this a static property at task launch?

-Tony