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b=PMrnpTMqfTNGy77Ve6cpOJPLTpaG1BSaXb77FTMa2BJ7XfCX3GSTu7WOIep1pbFWu DzFuO74vj7b8pC8U/g772fxSec0GaN4NmEJANjSqxvvz74mD0I6Oq68qv6GQvTT0mn NlRVdwUxd7vXNEUHzehDiM5/6Oi2HsiQz3s28QNQLyi0Rk/aZ2X7VIciMCyDUOFCmR naembNI4QBOdZoRFPwCEuYfe8G1CFWpXyAIC7yMlhwqQ2SAN7MysEvFN8k56wuhQFc LK6vvmPRnikQ/9vpIL+CL3NaW3y7w/tmqBbdzHqcfS6UqC1CqbZD+P83AOqT1MhLSn 0h03Q/guV/yjA== From: Michael Ellerman To: Baoquan He , linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, arnd@arndb.de, geert@linux-m68k.org, mcgrof@kernel.org, hch@infradead.org, Baoquan He , linux-alpha@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v3 2/2] arch/*/io.h: remove ioremap_uc in some architectures In-Reply-To: <20230303102817.212148-3-bhe@redhat.com> References: <20230303102817.212148-1-bhe@redhat.com> <20230303102817.212148-3-bhe@redhat.com> Date: Sun, 05 Mar 2023 20:23:05 +1100 Message-ID: <87sfej1rie.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: y5podnb1cydg9wy6337kxow93wq914rc X-Rspamd-Queue-Id: 07C2D4000B X-HE-Tag: 1678008192-328233 X-HE-Meta: U2FsdGVkX19mf252QxrcY7jhGIefNh8bhAMweCGr1mQ4NRopiRc2XMrmjQeS6lwACt0Ehlz7ixqvnyFfw/n9sv38D/3wgORZHGDvIZsNkH4rXzCtFl3ncMX7QQ9Kc8xmm4JaLLslOMCuzizYanj5zF/TCJV89whxjKGR2bc9ZqWvgXIm1+a1zYt2hr8f1fiShzimmoeME+gLwkwaMiXuuZRKT2zC5uQW0rmGgzTccayFJL8WsFxZf1A8NgMrAqvovzKQZyZO4KkPlQWypfep+ss9RQhsaGiHTXqavWBYgNp7JJbGajR1jw3hHmEvU+1x4cpVQ//4VfQdZQ75gDh7mVr6MGJJhcbSHkjzzzc2jpKrPXkXWDP4XKpio2Sb68v4X4/tSLUlAbYzBsIuaUy12Eutw9ux/X+Iso8OfhJSyNlPG/xD3ili6uG5B5RSs0pfv2Zbkki+q685y1tN6ob1Sa8dTk6l1Y7jC9MPx+weoGMFizDzHfQ3cQV1ftt9YqZRCQ6HENL84BbF4dOeq8m3LTMXTGrZmLr+bNdho8fndc6Ku7kgtzHO6IPFUwV/B/5sbnhRYQxaYXO/95O/QUtLpDKzcGyEjdXlE8IuGxrhWNC2iRqtXnxMGAwAqemzjOwaDQ7E2rGfCVUjMGytgizT4gC5RIHzFOqemyKztXr1xuDyKudVL7WsWG6BEO1k4WE9EBNlYKBgCsxkPqhq6RdPqVSfDE2Ug4uRpic2KQov7V/m4fG8f1dfEk95c5GpsU3sDzmrS5I3VzeybIbumC8uocekSET9nIpcge7L2Js6Tq2qu/mcNqVWWS/aUxWj2137wFPes/hvDzitUZHfCvzr9rVYqmLBTdmkfwdyMMfo3vHVLrDxe3jfb2pvw6dolC7cV0sVxtM3yfRg7QTvKHZwedpt7Bx0WPNbpank3DcasnxRuWV5KgOCFar9FD3+LV8DTyTsDPX+S3EFvzqHX7C IOLXH9hZ 32lNwV7I+pnVVi525W8kFgPQtKb56dUBGvxZWdkk2CBbtm1oRFuFYN1NMSVNv/w93w+TQr45SK8bRa6qzjR3iv/qmCDVsApVJIViSzgpSprjiXzWqrJgzr/LLN4oTIThDl6uvHZEh8PcZZaaV+jED4vSEnVHqGD0nt3DGrY3cWwNKHuQebBz+IPquFXXTg4fQqlKlJVY9NvCF0XhQZnsNlAi48d8EvnoROHHf 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: Baoquan He writes: > ioremap_uc() is only meaningful on old x86-32 systems with the PAT > extension, and on ia64 with its slightly unconventional ioremap() > behavior, everywhere else this is the same as ioremap() anyway. > > Here, remove the ioremap_uc() definition in architecutures other > than x86 and ia64. These architectures all have asm-generic/io.h > included and will have the default ioremap_uc() definition which > returns NULL. > > Note: This changes the existing behaviour and could break code > calling ioremap_uc(). If any ARCH meets this breakage and really > needs a specific ioremap_uc() for its own usage, one ioremap_uc() > can be added in the ARCH. I see one use in: drivers/video/fbdev/aty/atyfb_base.c: par->ati_regbase = ioremap_uc(info->fix.mmio_start, 0x1000); Which isn't obviously x86/ia64 specific. I'm pretty sure some powermacs (powerpc) use that driver. Maybe that exact code path is only reachable on x86/ia64? But if so please explain why. Otherwise it looks like this series could break that driver on powerpc at least. cheers