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Howlett" , vbabka , Suren Baghdasaryan , Ira Weiny , Nishanth Menon , heiko , Alexander Sverdlin , "Chester A. Unal" , Sergio Paracuellos , Andreas Larsson Message-ID: <1586788245.22320.1757533057730.JavaMail.zimbra@nod.at> In-Reply-To: References: <4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com> <497308537.21756.1757513073548.JavaMail.zimbra@nod.at> Subject: Re: [TECH TOPIC] Reaching consensus on CONFIG_HIGHMEM phaseout MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [195.201.40.130] X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF141 (Linux)/8.8.12_GA_3809) Thread-Topic: Reaching consensus on CONFIG_HIGHMEM phaseout Thread-Index: BY4xIXfJeETYMNF0Cnq/68k1mYFqTg== X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9264D1C0006 X-Stat-Signature: gwdesktdox589z5pw6t64frhj1azkocd X-HE-Tag: 1757533061-689798 X-HE-Meta: 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 mLnDWeFe IIbOZbTtlOBvTpLm2vClzgWs8Tsvrd++ikojXc8mhvvPzXp0Mu7TcaCvgpdWgbjl0b/N388Q4Kgm6SThtZJ3rCCAbrQOPS685O+GZJobMVPDOZnEWiDfHDf5cqY/xH/sZfIHCs496hKafqX2QEjLy9irLx1w9QKgu4yG+RiLnI58DqY0wGCPf7gESvO+7FzXzSwJuI8qKdknCVbvGYe++c4wj9c32gs4KTyqwgtD1o6lzKRALuOA7E07KK2VWb5GCyaDQH1q4cMWvym6z5VilKi4XI4Tke75rdq8V4lZYHiFF1nIM9x3HDrrIXcvwo2ULv5EJgabdqi6vTx12ymvcJJO1IbbkfnngpghRcLSIOQT9yuxrbFA1jDA43Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Christophe, ----- Urspr=C3=BCngliche Mail ----- > Von: "Christophe Leroy" > Can you tell which PPC32 model/family you are using ? Is it mpc85xx or > and/or other variants ? Maybe we can look at keeping CONFIG_HIGHMEM or > find alternatives for that subset of PPC32 only. Off the head, MPC8343 and QorIQ P1022. >=20 > Could you also elaborate a bit on the kind of issues you forsee or fear > with applications and FPGA device drivers. Unfortunately, applications in this area often make certain assumptions about the amount or layout of memory. This becomes a bigger problem when using FPGA device drivers of questionable quality, which share memory between the kernel, userspace, and the device itself. These are mostly out-of-tree drivers, so that's my horse to ride,=20 I'm just mentally preparing myself for "interesting" bugs that will need to be sorted out. > FWIW I sent out today a patch that removes CONFIG_HIGHMEM complely on > powerpc in order to get a better view of the impacted areas and allow > people to test what it looks like on their system without > CONFIG_HIGHMEM. See [1]. Oh, that was fast. :-) Thanks, //richard