From: Catalin Marinas <catalin.marinas@arm.com>
To: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Cc: Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Documentation/arm64: add memory layout with 4KB pages + VA39-bit
Date: Wed, 6 Oct 2021 18:14:38 +0100 [thread overview]
Message-ID: <YV3ZfmSHHKSWfDQu@arm.com> (raw)
In-Reply-To: <20210930185026.1609f12e@xhacker.debian>
On Thu, Sep 30, 2021 at 06:50:26PM +0800, Jisheng Zhang wrote:
> The 4KB pages + 3 levels (39-bit) combination is also widely used in
> arm64 world, add the memory layout description for this combination.
>
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> ---
> Documentation/arm64/memory.rst | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/Documentation/arm64/memory.rst b/Documentation/arm64/memory.rst
> index 901cd094f4ec..d1745b570f0c 100644
> --- a/Documentation/arm64/memory.rst
> +++ b/Documentation/arm64/memory.rst
> @@ -26,6 +26,23 @@ The swapper_pg_dir address is written to TTBR1 and never written to
> TTBR0.
>
>
> +AArch64 Linux memory layout with 4KB pages + 3 levels (39-bit)::
> + Start End Size Use
> + -----------------------------------------------------------------------
> + 0000000000000000 0000007fffffffff 512GB user
> + ffffff8000000000 ffffffbfffffffff 256GB kernel logical memory map
> + [ffffffb000000000 ffffffbfffffffff] 64GB [kasan shadow region]
> + ffffffc000000000 ffffffc007ffffff 128MB bpf jit region
> + ffffffc008000000 ffffffc00fffffff 128MB modules
> + ffffffc010000000 fffffffdefffffff 253440MB vmalloc
> + fffffffdf0000000 fffffffdfdffffff 224MB fixed mappings (top down)
> + fffffffdfe000000 fffffffdfe7fffff 8MB [guard region]
> + fffffffdfe800000 fffffffdff7fffff 16MB PCI I/O space
> + fffffffdff800000 fffffffdffffffff 8MB [guard region]
> + fffffffe00000000 ffffffffefffffff 4GB vmemmap
> + ffffffff00000000 ffffffffffffffff 4GB [guard region]
I wouldn't bother maintaining these. There are other combinations that
people may use. The 4KB + 48-bit VA is defconfig while 64KB + 52-bit was
more interesting, so we thought it would be useful.
I'm more inclined to remove them altogether and maybe just add some
high-level ascii art as per the log of commit f4693c2716b3 ("arm64: mm:
extend linear region for 52-bit VA configurations").
--
Catalin
next prev parent reply other threads:[~2021-10-06 17:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 10:50 [PATCH] Documentation/arm64: add memory layout with 4KB pages + VA39-bit Jisheng Zhang
2021-10-06 17:14 ` Catalin Marinas [this message]
2021-10-08 2:11 ` Jisheng Zhang
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