From: Stephen Warren <swarren@wwwdotorg.org>
To: Mian Yousaf Kaukab <ykaukab@suse.de>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, treding@nvidia.com,
jonathanh@nvidia.com, linux-tegra@vger.kernel.org
Subject: Re: [PATCH] arm64: tegra: only map accessible sysram
Date: Sun, 29 Sep 2019 23:28:43 -0600 [thread overview]
Message-ID: <5d2e47ec-8304-d648-9c4a-80c7c02050a9@wwwdotorg.org> (raw)
In-Reply-To: <20190929200851.14228-1-ykaukab@suse.de>
On 9/29/19 2:08 PM, Mian Yousaf Kaukab wrote:
> Most of the SysRAM is secure and only accessible by TF-A.
> Don't map this inaccessible memory in kernel. Only map pages
> used by bpmp driver.
I don't believe this change is correct. The actual patch doesn't
implement mapping a subset of the RAM (a software issue), but rather it
changes the DT representation of the SYSRAM hardware. The SYSRAM
hardware always does start at 0x30000000, even if a subset of the
address range is dedicated to a specific purpose. If the kernel must map
only part of the RAM, then some additional property should indicate
this. Also, I believe it's incorrect to hard-code into the kernel's DT
the range of addresses used by the secure monitor/OS, since this can
vary depending on what the user actually chooses to install as the
secure monitor/OS. Any indication of such regions should be filled in at
runtime by some boot firmware or the secure monitor/OS itself, or
retrieved using some runtime API rather than DT.
next prev parent reply other threads:[~2019-09-30 5:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-29 20:08 [PATCH] arm64: tegra: only map accessible sysram Mian Yousaf Kaukab
2019-09-30 5:28 ` Stephen Warren [this message]
2019-09-30 10:02 ` Mian Yousaf Kaukab
2019-10-02 20:30 ` Stephen Warren
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