[U-Boot] instruction "xchgb" for x86_64
Hi Simon, This is James and am working on u-boot to bring back MinGW tool chain for cross compiling host tools for Windows on Linux. After complete the code, I plan to generate a patch for community review. During work, I face an compiling error in file with macro CONFIG_IS_ENABLED. After some background study, seems this macro should not be available when compiling host tools. After check history, it's from 909780506773a9b09ae88cb267dbfa6a8d0caa7b on 2017-01-16 22:04:04, Below is the log message x86: Fix up byteorder.h for x86_64 Remove the very old x86 code and add support for 64-bit. Signed-off-by: Simon Glass mailto:s...@chromium.org>> Reviewed-by: Bin Meng bmeng...@gmail.com<mailto:bmeng...@gmail.com> Below are the relevant changes. +#define _constant_swab16(x) ((__u16)( \ + (((__u16)(x) & (__u16)0x00ffU) << 8) |\ + (((__u16)(x) & (__u16)0xff00U) >> 8))) + static __inline__ __u16 ___arch__swab16(__u16 x) { +#if CONFIG_IS_ENABLED(X86_64) + return _constant_swab16(x); +#else __asm__("xchgb %b0,%h0" /* swap bytes */ \ : "=q" (x) \ : "0" (x)); \ return x; +#endif } I am not familiar with x86 instructions and not understand the purpose of this change, is it because instruction "xchgb" not available on 64-bit architecture or something else? Thanks! Best regards James Wang Jinmin Rohde & Schwarz Asia Pte Ltd 9 Changi Business Park Vista, #01-01, Singapore 486 041 DID: 65-6307 0374Fax: 65-6307 0300 [ONE logo 2018_email] Privileged/Confidential information may be contained in this message. If you are not the intended recipient, Please notify the sender immediately and you must not use the message for any purpose nor disclose it to anyone. http://www.rohde-schwarz.com/sg P Please consider the environment before printing this email. <http://www.rohde-schwarz.com.sg/> ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] instruction "xchgb" for x86_64
Hi Bin >> This is James and am working on u-boot to bring back MinGW tool chain for >> cross compiling host tools for Windows on Linux. After complete the code, I >> plan to generate a patch for community review. >Do you mean cross compiling U-Boot's mkimage tool for Windows on Linux using >gcc-mingw-w64? Do you want to support building U-Boot on Windows as well? Yes, I am compiling with MinGW-w64, more specifically x86_64-w64-mingw32-gcc on Linux. I don't have setup to build host tools on Windows for now. Maybe I could have a try. Best regards James Wang Jinmin ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Re: [U-Boot] instruction "xchgb" for x86_64
> > Hi, > > (James please can you use plain-text email for the mailing list?) OK. Thanks Simon for pointing out this. I am using outlook, so most likely will have "newline" difference. Hope can find a way out for this. > > For chromebook_link64 I get: > > output: '/usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/arch/x86/include/asm/byteorder.h: > Assembler messages: > /usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/arch/x86/include/asm/byteorder.h:22: > Error: register type mismatch for `xchg' > make[2]: *** [/usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/scripts/Makefile.build:278: > net/tftp.o] Error 1 > make[2]: *** Waiting for unfinished jobs > /usr/local/google/home/sjg/cosarm/src/third_party/u-boot/files/net/net.c: > In function 'net_process_received_packet': > /usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/net/net.c:1324:1: > error: extended registers have no high halves } ^ > /usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/arch/x86/include/asm/byteorder.h: > Assembler messages: > /usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/arch/x86/include/asm/byteorder.h:22: > Error: register type mismatch for `xchg' > /usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/arch/x86/include/asm/byteorder.h:22: > Error: register type mismatch for `xchg' > /usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/arch/x86/include/asm/byteorder.h:22: > Error: register type mismatch for `xchg' > make[2]: *** [/usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/scripts/Makefile.build:278: > net/net.o] Error 1 > make[1]: *** [/usr/local/google/home/sjg/cosarm/src/third_party/u- > boot/files/Makefile:1588: > net] Error 2 > make[1]: *** Waiting for unfinished jobs > make: *** [Makefile:148: sub-make] Error 2 > > Perhaps there is another way to fix this? > I tested two toolchains: 1. With gcc version 7.3-win32 20180312 (the MinGW-w64 cross compiling), it can assemble the xchgb without error. 2. With gcc version 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04), it uses /usr/include/x86_64-linux-gnu/asm/byteorder.h, (not the one in uboot), and that file is only to include the file As the assembler you use reports error for xchgb (no matter what's the cause), we may use ONLY the C version of implementation and remove the assembly version and relevant CONFIG_IS_ENABLED checking (if performance is not critical here)? How do you think, Simon and Bin? Best regards James Wang Jinmin ___ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot