From: Arnd Bergmann <arnd@arndb.de>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Kalle Valo <kvalo@codeaurora.org>,
Thierry Reding <treding@nvidia.com>,
Andy Gross <agross@kernel.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: Re: [PATCH] iommu: fix ARM_SMMU vs QCOM_SCM compilation
Date: Mon, 11 Oct 2021 08:08:44 +0200 [thread overview]
Message-ID: <CAK8P3a3JwQP1b0KeLRN0UCMmzFn3+gY2oexYUwGyt2bOqC0P4A@mail.gmail.com> (raw)
In-Reply-To: <CAA8EJpoD4Th1tdwYQLnZur2oA0xX0LojSrNFLyJqdi6+rnB3YQ@mail.gmail.com>
On Mon, Oct 11, 2021 at 6:11 AM Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> wrote:
> On Sun, 10 Oct 2021 at 20:42, Arnd Bergmann <arnd@arndb.de> wrote:
>
> The patch seems correct, but it becomes overcomplicated. What about:
> - restoring QCOM_SCM stubs
The stubs are what has led to the previous bugs in this area to often
go unnoticed for too long, as illustrated by your suggestion
> - making ARM_SMMU select QCOM_SCM if ARM_SMMU_QCOM
I assume you meant "select QCOM_SCM if ARCH_QCOM",
after we stop using ARM_SMMU_QCOM?
> This would have almost the same result as with your patch, but without
> extra ARM_SMMU_QCOM Kconfig symbol.
The "almost" is the problem: consider the case of
CONFIG_ARM=y
CONFIG_COMPILE_TEST=y
CONFIG_ARCH_QCOM=n
CONFIG_ARM_SMMU=y
CONFIG_DRM_MSM=m
CONFIG_QCOM_SCM=m (selected by DRM_MSM)
The stubs here lead to ARM_SMMU linking against the QCOM_SCM
driver from built-in code, which fails because QCOM_SCM itself
is a loadable module.
We can move the "select QCOM_SCM" in the ARM_SMMU_QCOM
symbol if we make that a tristate though, if you want to separate it
a little more.
Arnd
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next prev parent reply other threads:[~2021-10-11 6:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-10 2:33 [PATCH] iommu: fix ARM_SMMU vs QCOM_SCM compilation Dmitry Baryshkov
2021-10-10 4:16 ` Bjorn Andersson
2021-10-10 17:42 ` Arnd Bergmann
2021-10-11 4:06 ` Steev Klimaszewski
2021-10-11 4:11 ` Dmitry Baryshkov
2021-10-11 6:08 ` Arnd Bergmann [this message]
2021-10-11 9:09 ` Dmitry Baryshkov
2021-10-11 9:56 ` Arnd Bergmann
2021-10-12 3:34 ` Dmitry Baryshkov
2021-10-12 3:35 ` Dmitry Baryshkov
2021-10-10 4:34 ` Steev Klimaszewski
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