On 11/15/2014 07:26 AM, Simon Glass wrote: > Hi Albert, > > On 14 November 2014 08:26, Albert ARIBAUD <albert.u.b...@aribaud.net> wrote: >> Hello Simon, >> >> On Fri, 14 Nov 2014 07:01:59 -0700, Simon Glass <s...@chromium.org> >> wrote: >>> Hi Victor, >>> >>> On 13 November 2014 09:29, Victor Ascroft <victorascr...@gmail.com> wrote: >>>> Hello, >>>> >>>> I am working with a Cortex A5 Freescale Vybrid Processor. Since a thumb >>>> build leads to a saving of almost 1 MB for my u-boot image and >>>> consequently to faster serial downloads I have been looking at this. >>>> Currently enabling this option leads to a hang. >>>> >>>> After some debugging I have narrowed the place of hang to "ldr pc, >>>> =board_init_r" in arch/arm/lib/crt0.S. My debugging procedure was to put a >>>> branch to a small function which just printed a small message with puts, >>>> just before the ldr instruction and then a printing a small message with >>>> puts just at the start of board_init_r in common/board_r.c . For a non >>>> thumb build, the two messages get printed and I can boot to the u-boot >>>> prompt. For a thumb build, only the first message before the ldr >>>> instruction gets printed. >>>> >>>> In crt0.S >>>> bl debug_print >>>> ldr pc, =board_init_r >>>> >>>> In board_init_r >>>> puts("In board_init_r\n"); // Right at start >>>> >>>> void debug_print(void) >>>> { >>>> // Defined in board file >>>> puts("Debug print\n"); >>>> } >>>> >>>> My assembly knowledge is limited and after some consultation with a senior >>>> colleague, he told me things to check. >>>> >>>> An object dump of the crt0.o shows a branch to an even address. For thumb, >>>> this is expected to be odd. To just try out, I did a change as below >>>> ldr r3, =board_init_r >>>> add r3, #1 >>>> bx r3 >>>> >>>> No change with this. My expectation was the compiler/linker/assembler >>>> would take care of the requirements, with the CONFIG_SYS_THUMB_BUILD. >>>> Frankly speaking I am not sure if this is the complete issue or only a >>>> part of it. I have seen patches with regards to OMAP send in by Aneesh V, >>>> which made changes of the form .type fn_name, %function to all the low >>>> level assembly functions, but, I couldn't dig up much more or variants >>>> thereof. Basically, from what I understand, this takes care of specifying >>>> .thumb_func for a thumb function or so to speak. >>>> >>>> Any pointers? >> >> Victor, >> >> In addition to Simon's question below on the toolchain, I would like to >> know which commit you're trying to build.
I am using u-boot 2014.10, but, I have a modified branch which supports my hardware and I also have changes for having USB Host and Client support for the Vybrid platform. The toolchain I am using is gcc-linaro-arm-linux-gnueabihf-2012.09-20120921 http://www.codesourcery.com/public/gnu_toolchain/arm-none-linux-gnueabi/arm-2009q3-67-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2 I have downloaded it from the above link. >> >>> I tried this on a peach_pi (Samsung Chromebook 2 13") and it worked OK >>> for me. The code sequence you refer to came out as below for me. >>> >>> 23e01e10 <clbss_l>: >>> 23e01e10: e1500001 cmp r0, r1 >>> 23e01e14: 35802000 strcc r2, [r0] >>> 23e01e18: 32800004 addcc r0, r0, #4 >>> 23e01e1c: 3afffffb bcc 23e01e10 <clbss_l> >>> 23e01e20: fa000dec blx 23e055d8 <coloured_LED_init> >>> 23e01e24: fb000deb blx 23e055da <red_led_on> >>> 23e01e28: e1a00009 mov r0, r9 >>> 23e01e2c: e5991030 ldr r1, [r9, #48] ; 0x30 >>> 23e01e30: e59ff008 ldr pc, [pc, #8] ; 23e01e40 >>> <clbss_l+0x30> >>> 23e01e34: 02073800 .word 0x02073800 >>> 23e01e38: 23e41eb0 .word 0x23e41eb0 >>> 23e01e3c: 23e77bf0 .word 0x23e77bf0 >>> 23e01e40: 23e057a9 .word 0x23e057a9 >>> >>> The 'ldr pc' line is loading from 23e01e40 which does have an odd address. >>> >>> What toolchain are you using? I tried with gcc 4.8.2 - including >>> linaro's 2013.10 release. >>> >>> In arch/arm/cpu/armv7/config.mk there is a fallback to armv5 from >>> armv7-a, and this may cause it to generate Thumb code instead of Thumb >>> 2. But you should get errors if that happens. >>> >>> It's hard to debug with such limited visibility. But if I put a puts() >>> at the start of board_init_r(), I see it on the serial console. >> >> Simon, >> >> I believe you've built crt0.S for ARM, not Thumb. > > Yes, but I suspect that is a function of the build system. I checked > the rest of U-Boot and most of it (including SPL) is Thumb 2. I > suppose we could use Thumb 2 for crt0.S if all the instructions are > supported. Yes Simon, you had it for ARM. I also believed it is a function of the build system. But, does crt0.S have to be in Thumb2? Thumb interop is not enough with ARM and Thumb co-existing? Does CONFIG_SYS_THUMB_BUILD require any specific changes to the build system. I was under the impression, the configuration would take care of it. I can do any changes are required, but, I have no knowledge of it. > > Regards, > Simon > Regards, Victor. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot