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[150.31.62.179]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84e172376ebsm4324439b3a.12.2026.07.24.00.16.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Jul 2026 00:16:37 -0700 (PDT) Date: Fri, 24 Jul 2026 16:16:36 +0900 Message-ID: From: Hajime Tazaki To: johannes@sipsolutions.net Cc: linux-um@lists.infradead.org, liam@infradead.org, ljs@kernel.org, ricarkol@google.com Subject: Re: [PATCH v2 04/10] um: change machine name for uname output In-Reply-To: References: <20260723093633.140989-12-johannes@sipsolutions.net> <20260723113633.bcaf234695c5.I226381aaaf6dd46c559b0e694b29370d0102ce3f@changeid> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/26.3 Mule/6.0 MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260724_001654_894859_804DF748 X-CRM114-Status: GOOD ( 21.74 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org On Fri, 24 Jul 2026 15:54:30 +0900, Johannes Berg wrote: > > On Fri, 2026-07-24 at 15:50 +0900, Hajime Tazaki wrote: > > On Thu, 23 Jul 2026 18:35:45 +0900, > > Johannes Berg wrote: > > > > > > From: Hajime Tazaki > > > > > > This commit tries to display MMU/!MMU mode from the output of uname(2) > > > so that users can distinguish which mode of UML is running right now. > > > > > > Signed-off-by: Hajime Tazaki > > > [remove / to fix regression with systemd userspace] > > > Signed-off-by: Johannes Berg > > > --- > > > v2: regression fix > > > > I'd like to know what kind of regression did you see. > > With your original change, systemd doesn't boot, it asserts here: > https://github.com/systemd/systemd/blob/main/src/basic/architecture.c#L136 thanks, > > with only this diff, there is no visible changes with uname command on > > UML (both mmu/nommu), as setup_machinename() overwrite this. > > Oops. I never tested it, sorry. Just saw the boot failure with my > standard 64-bit (and maybe 32-bit as well?) boot test filesystems. > > > maybe we could drop this patch if we cannot put a name 'um' in the > > machine name ? > > Sure, we can drop it. Or arrange so only nommu is different? Or even > call it SUBARCH-nommu? systemd detects UML via systemd-detect-virt, not `uname -m`: https://github.com/obbardc/systemd/blob/master/src/basic/virt.c#L298 it looks like it uses vendor_id field of /proc/cpuinfo. I guess they are right. my original intention for this patch (to uname output) is to avoid confusion (of myself) which UML (MMU or NOMMU) I am running so, it's purely a kind of debugging purpose. I think we can drop it and come back later if we really need to provide a way to detect nommu UML (probably extending show_cpuinfo()). -- Hajime