From: "David Hildenbrand (Arm)" <david@kernel.org>
To: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hajime Tazaki <thehajime@gmail.com>,
johannes@sipsolutions.net, linux-mm@kvack.org,
liam@infradead.org, rbm@suse.com, akpm@linux-foundation.org,
luto@amacapital.net, brendan.jackman@linux.dev,
liuhangbin@gmail.com, corbet@lwn.net, kees@kernel.org,
broonie@kernel.org, mhocko@suse.com, rppt@kernel.org,
shuah@kernel.org, surenb@google.com, vbabka@kernel.org,
wad@chromium.org, linux-doc@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-um@lists.infradead.org,
daniel@thingy.jp
Subject: Re: [PATCH v4 1/2] selftests: run tests on nommu architecture
Date: Fri, 2 Oct 2026 14:21:53 +0200 [thread overview]
Message-ID: <d6ee0a8f-e7a8-4fa7-88b8-62fb44bfc863@kernel.org> (raw)
In-Reply-To: <ar-bIzYDdlOKUqla@gremlin>
On 10/2/26 13:53, Lorenzo Stoakes (ARM) wrote:
> On Fri, Oct 02, 2026 at 01:38:31PM +0200, Geert Uytterhoeven wrote:
>
>> On Fri, 2 Oct 2026 at 10:10, Lorenzo Stoakes (ARM) <ljs@kernel.org> wrote:
>
>>> But fork() -> -EINVAL or -ENOSYS = nommu, then just have the child quit and
>>> etc. should do it.
>>
>> fork() is not strictly an MMU-feature (you can implement fork on nommu
>> if all memory accesses are done relative to a base address register),
>> while I think mprotect() is an MMU-feature. Unless it can also be used
>> to change the protection using the one or two BARs most MCU haves?
>> Anything else that is a real MMU-feature? Non-identity mmap()?
>
> Does any nommu arch implement fork() in linux?
I was about to say, that sounds a bit too theoretical for me. IIUC that is not
implemented, and if someone would propose it we would likely just nak it.
In the unlikely event that this would see the light of day, we could always
change our detection in the selftests.
--
Cheers,
David
next prev parent reply other threads:[~2026-10-02 12:22 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-29 23:57 [PATCH v4 0/2] support kselftest on nommu platform Hajime Tazaki
2026-09-29 23:57 ` [PATCH v4 1/2] selftests: run tests on nommu architecture Hajime Tazaki
2026-09-30 9:17 ` Lorenzo Stoakes (ARM)
2026-10-01 7:08 ` David Hildenbrand (Arm)
2026-10-01 8:42 ` Lorenzo Stoakes (ARM)
2026-10-01 10:01 ` Johannes Berg
2026-10-02 2:38 ` Hajime Tazaki
2026-10-02 6:08 ` David Hildenbrand (Arm)
2026-10-02 8:10 ` Lorenzo Stoakes (ARM)
2026-10-02 11:38 ` Geert Uytterhoeven
2026-10-02 11:53 ` Lorenzo Stoakes (ARM)
2026-10-02 12:21 ` David Hildenbrand (Arm) [this message]
2026-10-03 22:39 ` Hajime Tazaki
2026-09-29 23:57 ` [PATCH v4 2/2] selftests/nommu: add nommu mmap and mremap behavior tests Hajime Tazaki
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