From: "Arnd Bergmann" <arnd@arndb.de>
To: "Qingfang Deng" <qingfang.deng@linux.dev>
Cc: Linux-Arch <linux-arch@vger.kernel.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
"Vikram Sethi" <vsethi@nvidia.com>,
"Mike Rapoport" <rppt@kernel.org>,
"Shanker Donthineni" <sdonthineni@nvidia.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] arm64: use generic MMIO accessors
Date: Sun, 20 Sep 2026 11:35:36 +0200 [thread overview]
Message-ID: <114d7d69-dd0a-499a-8cd5-732baa21c74c@app.fastmail.com> (raw)
In-Reply-To: <3250a625-7900-40a9-8f3c-612d333122dc@app.fastmail.com>
On Sun, Sep 20, 2026, at 11:30, Arnd Bergmann wrote:
> On Sun, Sep 20, 2026, at 11:24, Qingfang Deng wrote:
>>
>> Regarding unaligned accesses, the splitting can only happen when the
>> address is known to be unaligned at compile-time. Do these accessors
>> need to support unaligned MMIO? If so, I could add
>> OPTIMIZER_HIDE_VAR(addr) to the generic accessors.
>
> I think all architectures that have had this problem just started
> using the inline asm variant, and I'd probably try to encourage
> that more.
Also, I have only seen this problem in combination with driver bugs
that define their MMIO registers as a __packed data structure
instead of the usual 'void __iomem*' with constant offset or a
normal structure without packing.
Arnd
next prev parent reply other threads:[~2026-09-20 9:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-20 1:43 [PATCH v2 1/3] asm-generic: split MMIO accessors out of io.h Qingfang Deng
2026-09-20 1:43 ` [PATCH v2 2/3] riscv: use generic MMIO accessors Qingfang Deng
2026-09-20 8:11 ` Arnd Bergmann
2026-09-20 1:43 ` [PATCH v2 3/3] arm64: " Qingfang Deng
2026-09-20 8:08 ` Arnd Bergmann
2026-09-20 9:24 ` Qingfang Deng
2026-09-20 9:30 ` Arnd Bergmann
2026-09-20 9:35 ` Arnd Bergmann [this message]
2026-09-20 8:13 ` [PATCH v2 1/3] asm-generic: split MMIO accessors out of io.h Arnd Bergmann
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