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[14.202.190.183]) by smtp.gmail.com with ESMTPSA id o11sm3241399pgh.78.2020.03.19.19.02.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Mar 2020 19:02:20 -0700 (PDT) Date: Fri, 20 Mar 2020 12:00:13 +1000 From: Nicholas Piggin Subject: Re: [RFC PATCH] powerpc/64s: CONFIG_PPC_HASH_MMU To: linuxppc-dev@lists.ozlabs.org, Michael Ellerman References: <20200302044902.3418935-1-npiggin@gmail.com> <878sjxdlpa.fsf@mpe.ellerman.id.au> In-Reply-To: <878sjxdlpa.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 User-Agent: astroid/0.15.0 (https://github.com/astroidmail/astroid) Message-Id: <1584667943.t0isihrd3v.astroid@bobo.none> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Michael Ellerman's on March 19, 2020 2:15 pm: > Nicholas Piggin writes: >> This allows the 64s hash MMU code to be compiled out if radix is >> selected. This saves about 128kB kernel image size (90kB text) on >> powernv_defconfig minus KVM, 40kB on a tiny config. >=20 > TBH my feelings are: > - the size savings don't excite me much, given our kernels can be ~32MB > in size. > - it's unlikely a major (or any) distro would ever enable this, so it > would not be well tested. Yeah, it would only really be used for firmware or certain embedded=20 things. We'd want some actual user before it's merged. > - it adds a *lot* of #ifdefs. Yeah I started to get lazy, we can improve those quite a bit I think. > So if we want to get this merged I'd want a good amount of refactoring > done to avoid the bulk of the #ifdefs in the code. ie. lots of wrapper > inlines etc. to hide the #ifdefs. >=20 > And someone to put up their hand to maintain it, ie. ensure it keeps > building and fix any issues that come up when it breaks. Yeah, I'll keep tinkering on it, it might come in useful. Thanks, Nick =