From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1522338228; cv=none; d=google.com; s=arc-20160816; b=pexOoCUb4EAXqlWij2EXUgws8SZfZ/8Sv2EiT6HiI8/VtuQ6khpbHS1bRyO0GHhH1K vEanuWITU7dMgFInWdZJCr/8Tq9Vl7E04RKZ4NgGX04N6ugoe5+fl7efq4JoltlC0kwr vYFAb6ILJwRfEY5m6QX5tI0GmTNdyVjydDFpK42YITLT0ao0Srx2x0slH76XeuAen4+6 0Ao8+ud8aC7/SnnbjK8WevDkV64EsIhPYLsDMrjVePj4DGtHYi26lJUDXWO4IGCdfn1n 5PVi5+0+WopGJbQsqJmOuaKoFlCdiBoHClYve2g2LNCCuSedYfSnmX8jGXWl1QyBbTjN kzdA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to:sender :mime-version:dkim-signature:arc-authentication-results; bh=NHAZZEXjkRfAu0OaItrJR1Fls26X0hu/wuX9yKcQkw8=; b=jOSBQNVF4Nw74oIC92mF73UqlHvVuP6stxepEbvDJh/MUFdb28u60Don99kbZUi+cu toET26ecdoJKYj7X2oE2zaCACc08A+wcPtDgxRwdR/rJiHcI24v8AUZ1K7adA4MC9UnC 5OLHhiTV3NYwKa4civhaRU2/AIq4SUrzTMAXSz4Cc1hk9Rg4c0XwkHgANHGhooGlhGgI 19A9KAl1/9wjHRyjwlhYHwhldnbr70kmXFZComwBO3H1s1GPEa36/OEvVHr5gawZgt0u Mct8iBMPrRg9BB1tcRSH/3Cg7FQCPwWlmjCie5n3dBAWjYm1pUAeXmBRtfZEChAQsF7X uzYA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=KsYle7dh; spf=pass (google.com: domain of geert.uytterhoeven@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=geert.uytterhoeven@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=KsYle7dh; spf=pass (google.com: domain of geert.uytterhoeven@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=geert.uytterhoeven@gmail.com X-Google-Smtp-Source: AIpwx49JBd3+SBMgHXCH8d7Idg12FurIjLqmPTmIhI/z7T+oUxi95TuzVNqjMJDng2+WbzjQYp6HlMO+wJtMk4xMh60= MIME-Version: 1.0 Sender: geert.uytterhoeven@gmail.com In-Reply-To: <20180329152749.GC16141@n2100.armlinux.org.uk> References: <20180325221853.10839-1-shea@shealevy.com> <20180328152714.6103-1-shea@shealevy.com> <05620fee-e8b5-0668-77b8-da073dc78c40@landley.net> <20180328164813.GA3888@n2100.armlinux.org.uk> <20180328221401.GA14084@n2100.armlinux.org.uk> <20180329152749.GC16141@n2100.armlinux.org.uk> From: Geert Uytterhoeven Date: Thu, 29 Mar 2018 17:43:47 +0200 X-Google-Sender-Auth: XR_k5aiSoT5iFZQuDvDX6ovvWKU Message-ID: Subject: Re: [PATCH] Extract initrd free logic from arch-specific code. To: Russell King - ARM Linux Cc: Oliver , Rob Landley , Shea Levy , linux-riscv@lists.infradead.org, Linux Kernel Mailing List , Christoph Hellwig , Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Catalin Marinas , Will Deacon , Mark Salter , Aurelien Jacquiot , Mikael Starvik , Jesper Nilsson , Yoshinori Sato , Richard Kuo , Tony Luck , Fenghua Yu , James Hogan , Michal Simek , Ralf Baechle , David Howells , Ley Foon Tan , Jonas Bonn , Stefan Kristiansson , Stafford Horne , "James E.J. Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Palmer Dabbelt , Albert Ou , Martin Schwidefsky , Heiko Carstens , Chen Liqin , Lennox Wu , Rich Felker , "David S. Miller" , Jeff Dike , Richard Weinberger , Guan Xuetao , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "the arch/x86 maintainers" , Chris Zankel , Max Filippov , Kate Stewart , Greg Kroah-Hartman , Philippe Ombredanne , Eugeniy Paltsev , Al Viro , Vladimir Murzin , Linus Walleij , Michal Hocko , Andrew Morton , Sudip Mukherjee , Marc Zyngier , Rob Herring , Kees Cook , Vlastimil Babka , Balbir Singh , Christophe Leroy , Joe Perches , Dan Williams , Wei Yang , =?UTF-8?Q?Christian_K=C3=B6nig?= , Arnd Bergmann , Deepa Dinamani , Daniel Thompson , Florian Fainelli , alpha , arcml , Linux ARM , adi-buildroot-devel@lists.sourceforge.net, linux-c6x-dev@linux-c6x.org, Cris , "moderated list:H8/300 ARCHITECTURE" , "open list:QUALCOMM HEXAGON..." , linux-ia64@vger.kernel.org, linux-m68k , "open list:METAG ARCHITECTURE" , Linux MIPS Mailing List , "moderated list:PANASONIC MN10300..." , nios2-dev@lists.rocketboards.org, Openrisc , Parisc List , linuxppc-dev , linux-s390 , Linux-sh list , sparclinux , uml-devel , uml-user , linux-xtensa@linux-xtensa.org, Nicholas Piggin Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1596195734883590774?= X-GMAIL-MSGID: =?utf-8?q?1596287330678551696?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, Mar 29, 2018 at 5:27 PM, Russell King - ARM Linux wrote: > On Thu, Mar 29, 2018 at 09:37:52AM +1100, Oliver wrote: >> On Thu, Mar 29, 2018 at 9:14 AM, Russell King - ARM Linux >> wrote: >> > On Wed, Mar 28, 2018 at 02:04:22PM -0500, Rob Landley wrote: >> >> On 03/28/2018 11:48 AM, Russell King - ARM Linux wrote: >> >> > On Wed, Mar 28, 2018 at 10:58:51AM -0500, Rob Landley wrote: >> >> >> On 03/28/2018 10:26 AM, Shea Levy wrote: >> >> >>> Now only those architectures that have custom initrd free requirements >> >> >>> need to define free_initrd_mem. >> >> >> ... >> >> >>> --- a/arch/arc/mm/init.c >> >> >>> +++ b/arch/arc/mm/init.c >> >> >>> @@ -229,10 +229,3 @@ void __ref free_initmem(void) >> >> >>> { >> >> >>> free_initmem_default(-1); >> >> >>> } >> >> >>> - >> >> >>> -#ifdef CONFIG_BLK_DEV_INITRD >> >> >>> -void __init free_initrd_mem(unsigned long start, unsigned long end) >> >> >>> -{ >> >> >>> - free_reserved_area((void *)start, (void *)end, -1, "initrd"); >> >> >>> -} >> >> >>> -#endif >> >> >>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> >> >>> index 3f972e83909b..19d1c5594e2d 100644 >> >> >>> --- a/arch/arm/Kconfig >> >> >>> +++ b/arch/arm/Kconfig >> >> >>> @@ -47,6 +47,7 @@ config ARM >> >> >>> select HARDIRQS_SW_RESEND >> >> >>> select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT) >> >> >>> select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6 >> >> >>> + select HAVE_ARCH_FREE_INITRD_MEM >> >> >>> select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU >> >> >>> select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU >> >> >>> select HAVE_ARCH_MMAP_RND_BITS if MMU >> >> >> >> >> >> Isn't this why weak symbols were invented? >> >> > >> >> > Weak symbols means that we end up with both the weakly-referenced code >> >> > and the arch code in the kernel image. That's fine if the weak code >> >> > is small. >> >> >> >> The kernel's been able to build with link time garbage collection since 2016: >> >> >> >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b67067f1176d >> >> >> >> Wouldn't that remove the unused one? >> > >> > Probably, if anyone bothered to use that, which they don't. >> > >> > LD_DEAD_CODE_DATA_ELIMINATION is a symbol without a prompt, and from >> > what I can see, nothing selects it. Therefore, the symbol is always >> > disabled, and so the feature never gets used in mainline kernels. >> > >> > Brings up the obvious question - why is it there if it's completely >> > unused? (Maybe to cause confusion, and allowing a justification >> > for __weak ?) >> >> IIRC Nick had some patches to do the arch enablement for powerpc, but >> I'm not sure what happened to them though. I suspect it just fell down >> Nick's ever growing TODO list. > > I've given it a go on ARM, marking every linker-built table with KEEP() > and comparing the System.map files. The resulting kernel is around > 150k smaller, which seems good. > > However, it doesn't boot - and I don't know why. Booting the kernel > under kvmtool in a VM using virtio-console, I can find no way to get > any kernel messages out of it. Using lkvm debug, I can see that the > PC is stuck inside die(), and that's the only information I have. > It dies before bringing up the other CPUs, so it's a very early death. > > I don't think other console types are available under ARM64. earlycon? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds