From: Robin Murphy Subject: Re: [PATCH RFC 0/3] API for 128-bit IO access Date: Thu, 25 Jan 2018 12:11:14 +0000 Message-ID: <8999df0f-910a-21f8-e66d-3deedecdad3d@arm.com> References: <20180125113843.vgv6kyp7qjd75qif@yury-thinkpad> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-arch , Andrew Pinski , Kees Cook , Sunil Goutham , Jeffrey Walton , Catalin Marinas , Will Deacon , Linux Kernel Mailing List , Nicholas Piggin , Ingo Molnar , Geethasowjanya Akula , Al Viro , Greg Kroah-Hartman , Andrew Morton , Laura Abbott , "David S . Miller" , Linux ARM , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE To: Yury Norov , Arnd Bergmann Return-path: Received: from foss.arm.com ([217.140.101.70]:34978 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902AbeAYMLT (ORCPT ); Thu, 25 Jan 2018 07:11:19 -0500 In-Reply-To: <20180125113843.vgv6kyp7qjd75qif@yury-thinkpad> Content-Language: en-GB Sender: linux-crypto-owner@vger.kernel.org List-ID: On 25/01/18 11:38, Yury Norov wrote: > On Wed, Jan 24, 2018 at 11:28:55AM +0100, Arnd Bergmann wrote: >> On Wed, Jan 24, 2018 at 10:05 AM, Yury Norov wrote: >>> This series adds API for 128-bit memory IO access and enables it for ARM64. >>> The original motivation for 128-bit API came from new Cavium network device >>> driver. The hardware requires 128-bit access to make things work. See >>> description in patch 3 for details. >> >> We might also want to do something similar to the >> include/linux/io-64-nonatomic-lo-hi.h >> and hi-lo.h files, to simulate 128-bit access using pairs of 64-bit access on >> other targets. It's apparently driver specific which half you need to do first >> to make it work, so we need both. > > OK, will do. > >>> Also, starting from ARMv8.4, stp and ldp instructions become atomic, and >>> API for 128-bit access would be helpful in core arm64 code. >>> >>> This series is RFC. I'd like to collect opinions on idea and implementation >>> details. >>> * I didn't implement all 128-bit operations existing for 64-bit variables >>> and other types (__swab128p etc). Do we need them all right now, or we >>> can add them when actually needed? >> >> I think in this case it's better to do them all at once. > > Ack. > >>> * u128 name is already used in crypto code. So here I use __uint128_t that >>> comes from GCC for 128-bit types. Should I rename existing type in crypto >>> and make core code for 128-bit variables consistent with u64, u32 etc? (I >>> think yes, but would like to ask crypto people for it.) >> >> Hmm, that file probably predates the __uint128_t support. My guess would >> be that the crypto code using it can actually benefit from the new types as >> well, so maybe move the existing file to include/linux/int128.h and add >> an #if/#else logic to it so we use 'typedef __uint128_t __u128' if that >> is available. > > It sounds reasonable. But I worry about testing that changes. Hope, > crypto community will help with it. > >>> * Some compilers don't support __uint128_t, so I protected all generic code >>> with config option HAVE_128BIT_ACCESS. I think it's OK, but... >> >> That would be nicely solved by using the #if/#else definition above. >> >>> * For 128-bit read/write functions I take suffix 'o', which means read/write >>> the octet of bytes. Is this name OK? >> >> Can't think of anything better. It's not an octet though, but 16 bytes >> ('q' is for quadword, meaning four 16-bit words in Intel terminology). > > Ah, sure. Octet of words. Will change it. > >>> * my mips-linux-gnu-gcc v6.3.0 doesn't support __uint128_t, and I >>> don't have other BE setup on hand, so BE case is formally not tested. >>> BE code for arm64 is looking well though. >> >> I've run it through my collection of compilers, it seems that most but not >> all 64-bit targets support it (exceptions appear to be older versions of >> gcc for s390x and parisc), and none of the 32-bit targets do: > > Thanks for doing this test. Looking at this I realize that this is > not the architecture feature but compiler feature. So if we add > 128-bit interface, it would be reasonable to add it for all targets > that compiled with toolchain supporting 128-bit accesses. > > There's already the option ARCH_SUPPORTS_INT128 that is enabled for > x86_64 in arch/x86/Kconfig and conditionally enabled for arm64 in > arch/arm64/Makefile: > KBUILD_CFLAGS += $(call cc-ifversion, -ge, 0500, -DCONFIG_ARCH_SUPPORTS_INT128) > > It is used in include/linux/math64.h and in lib/ubsan.c, not so wide. > > So I find things little messed. Crypto code ignores compilers' ability > to operate with 128-bit numbers. Ubsan and math64 relies on compiler > version (at least for arm64, and I doubt it would work correctly with clang). > And now I introduce HAVE_128BIT_ACCESS with the same meaning for memory > access. > > I think it's time to unify 128-bit code: > - enable CONFIG_ARCH_SUPPORTS_INT128 if compiler supports it, ie check > it like you do below; > - declare u128 as structure or typedef depending on ARCH_SUPPORTS_INT128 > in generic include/linux/int128.h, as you suggest here; > - switch this series to ARCH_SUPPORTS_INT128. > > Does it sound reasonable? It probably is about time to formalise the current scattered fragments of uint_128_t support, but to reiterate Will's comment it is almost certainly not worth the effort to implement 'generic' I/O accessors which only work under implementation-defined and undiscoverable hardware conditions, and will be unusable on the overwhelming majority of systems. Just open-code LDP/STP accessors in the one driver which needs them and (by definition) only runs on SoCs where they *are* known to work correctly. Robin. > > Yury > >> $ for i in /home/arnd/cross-gcc/bin/*gcc-[3-8]* ; do echo -n $i" " ; >> echo '__uint128_t v;' | $i -xc -S - -o /dev/null && echo ok ; done >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-4.8.5 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-4.9.3 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-4.9.4 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-5.2.1 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-5.4.1 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-5.5.0 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-6.3.1 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-7.0.0 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-7.0.1 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-7.1.1 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/aarch64-linux-gcc-8.0.0 ok >> /home/arnd/cross-gcc/bin/alpha-linux-gcc-4.1.3 ok >> /home/arnd/cross-gcc/bin/alpha-linux-gcc-4.3.6 ok >> /home/arnd/cross-gcc/bin/alpha-linux-gcc-4.9.3 ok >> /home/arnd/cross-gcc/bin/alpha-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/am33_2.0-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/am33_2.0-linux-gcc-5.2.1 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/am33_2.0-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/arc-elf-gcc-7.2.1 :1:1: error: unknown >> type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-3.4.6 ok >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.4.7 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.5.4 :1:13: >> error: expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.6.4 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.7.4 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.8.5 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.9.0 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.9.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.9.2 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.9.3 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-4.9.4 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-5.0.0 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-5.1.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-5.2.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-5.3.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-5.4.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-5.5.0 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-6.0.0 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-6.1.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-6.3.1 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-7.0.0 :1:1: >> error: unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-7.0.1 :1:1: >> error: unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-7.1.1 :1:1: >> error: unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-7.2.1 :1:1: >> error: unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-gcc-8.0.0 :1:1: >> error: unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/bfin-uclinux-gcc-7.0.0 >> bfin-uclinux-gcc-7.0.0: error trying to exec 'cc1': execvp: No such >> file or directory >> /home/arnd/cross-gcc/bin/bfin-uclinux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/c6x-elf-gcc-7.2.1 :1:1: error: unknown >> type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/cris-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/cris-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/cris-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/cris-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/frv-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/frv-linux-gcc-4.3.6 :1: internal >> compiler error: in default_secondary_reload, at targhooks.c:618 >> Please submit a full bug report, >> with preprocessed source if appropriate. >> See for instructions. >> /home/arnd/cross-gcc/bin/frv-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/frv-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/h8300-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/hppa64-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/hppa64-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/hppa-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/hppa-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/hppa-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/hppa-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/i386-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/i386-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/ia64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/m32r-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/m32r-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/m32r-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/m32r-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/m68k-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/m68k-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/m68k-linux-gcc-6.0.0 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/m68k-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/microblaze-linux-gcc-4.9.3 :1:1: >> error: unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/microblaze-linux-gcc-7.2.1 :1:1: >> error: unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/mips64-linux-gcc-4.9.3 ok >> /home/arnd/cross-gcc/bin/mips64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/mips-linux-gcc-4.0.4 :1: error: syntax >> error before 'v' >> :1: warning: data definition has no type or storage class >> /home/arnd/cross-gcc/bin/mips-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/mips-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/mips-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/mips-linux-gcc-7.0.0 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/mips-linux-gcc-7.0.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/mips-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/nios2-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/parisc-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/powerpc64-linux-gcc-4.1.3 ok >> /home/arnd/cross-gcc/bin/powerpc64-linux-gcc-4.3.6 ok >> /home/arnd/cross-gcc/bin/powerpc64-linux-gcc-4.9.3 ok >> /home/arnd/cross-gcc/bin/powerpc64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/powerpc-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/powerpc-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/riscv32-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/riscv64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/s390-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/s390-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/s390-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/s390-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/sh2-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/sh3-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/sh3-linux-gcc-4.3.6 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/sh3-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/sh4-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/sh-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/sparc64-linux-gcc-4.9.3 ok >> /home/arnd/cross-gcc/bin/sparc64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/sparc-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/sparc-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/sparc-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/tilegx-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/tilepro-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-3.4.6 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.0.4 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.1.3 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.2.5 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.3.6 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.4.7 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.5.4 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.6.4 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.7.4 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.8.5 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.9.3 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-4.9.4 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-5.4.1 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-5.5.0 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-6.1.1 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-6.3.1 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-7.0.0 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-7.0.1 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-7.1.1 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-7.2.1 ok >> /home/arnd/cross-gcc/bin/x86_64-linux-gcc-8.0.0 ok >> /home/arnd/cross-gcc/bin/xtensa-linux-gcc-4.1.3 :1: error: >> expected '=', ',', ';', 'asm' or '__attribute__' before 'v' >> /home/arnd/cross-gcc/bin/xtensa-linux-gcc-4.9.3 :1:1: error: >> unknown type name '__uint128_t' >> /home/arnd/cross-gcc/bin/xtensa-linux-gcc-7.2.1 :1:1: error: >> unknown type name '__uint128_t'; did you mean '__int128'? > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >