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[221.241.217.81]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-77f613dbc5csm1372022b3a.59.2025.09.23.16.58.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Sep 2025 16:58:51 -0700 (PDT) Date: Wed, 24 Sep 2025 08:58:47 +0900 Message-ID: From: Hajime Tazaki To: johannes@sipsolutions.net Cc: hch@infradead.org, benjamin@sipsolutions.net, linux-um@lists.infradead.org, w@1wt.eu, linux@weissschuh.net, linux-kselftest@vger.kernel.org, acme@redhat.com, linux-kernel@vger.kernel.org, benjamin.berg@intel.com Subject: Re: [PATCH v2 00/11] Start porting UML to nolibc In-Reply-To: <4354d88c2ff7a57a7324cc39b4ce5ed4ebe5277d.camel@sipsolutions.net> References: <20250919153420.727385-1-benjamin@sipsolutions.net> <4354d88c2ff7a57a7324cc39b4ce5ed4ebe5277d.camel@sipsolutions.net> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII Hello Benjamin, Johannes, On Mon, 22 Sep 2025 16:41:36 +0900, Johannes Berg wrote: > > On Fri, 2025-09-19 at 08:40 -0700, Christoph Hellwig wrote: > > On Fri, Sep 19, 2025 at 05:34:09PM +0200, Benjamin Berg wrote: > > > From: Benjamin Berg > > > > > > This patchset is an attempt to start a nolibc port of UML. > > > > It would be useful to explain why that is desirable. > > Agree, it should be here, but FWIW it's been discussed elsewhere on the > linux-um list in the past and basically there are various issues around > it. Off the top of my head: > - glibc enabling new features such as rseq that interact badly with how > UML manages memory (there were fixes for this, it worked sometimes > and sometimes not) > - allocation placement for TLS is problematic (see the SMP series) > - it's (too) easy to accidentally call glibc functions that require > huge amounts of stack space > > There are probably other reasons, but the mixed nature of UML being both > kernel and "hypervisor" code in a single place doesn't mix well with > glibc. just curious - are those issues not happening in other libc implementation ? (e.g., musl-libc) - same question to nolibc: is there any possibility that nolibc will evolve as glibc does, and this evolution introduces the UML issues ? -- Hajime