I’m writing software for a Cortex-A8 processor and I have to write some ARM assembly code to access specific registers. I’m making use of the gnu compilers and related tool chains, these tools are installed on the processor board(Freescale i.MX515) with Ubuntu. I make a connection to it from my host PC(Windows) using WinSCP and the PuTTY terminal.<\/p>\n
As usual I started with a simple C project having main.c<\/strong> and functions.s<\/strong>. I compile<\/strong> the main.c using GCC<\/strong>, assemble<\/strong> the functions.s using as<\/strong> and link<\/strong> the generated object files using once again GCC<\/strong>, but I get strange errors during this process.<\/p>\n An important finding –<\/strong><\/p>\n Meanwhile, I found out that my assembly code may have some issues because when I individually assemble it using the command Can anyone suggest whats happening here? Are there any specific options I have to send, to GCC<\/strong> during the linking process? The errors I see are strange and beyond my understanding, I don’t understand to what the GCC is referring.<\/p>\n I’m pasting here the contents of main.c, functions.s, the Makefile and the list of errors.<\/p>\n Latest errors included after the makfile was edited as suggested by guys here –<\/strong><\/p>\n main.c<\/strong><\/p>\n functions.s<\/strong><\/p>\n Makefile<\/strong><\/p>\n — hello was included here after suggested here by guys at stackoverflow, but the problem still persists, I still get the same errors.<\/p>\n Errors<\/strong><\/p>\n In the makefile:<\/p>\n should be:<\/p>\n As it stands, you are linking functions.o, but not main.o, and producing an output executable called main.o, which is overwriting your existing main.o.<\/p>\n<\/li>\n Shouldn’t<\/p>\n be<\/p>\n As Bigbohne suggests, gcc is trying to link in the standard runtime library. Try adding the -nostdlib option to your gcc call:<\/p>\n I think that has something to do with the Runtime library the gcc is linking at the end.<\/p>\n And in this<\/strong> library there already is a “_start”.<\/p>\n I think you have to compile without “std library”. but than you wont have printf,getchar and all the other useful stuff.<\/p>\n<\/li>\n<\/ol>\n Originally posted 2013-11-09 23:14:16. <\/small><\/p>","protected":false},"excerpt":{"rendered":" I’m writing software for a Cortex-A8 processor and I have to write some ARM assembly code to access specific registers. I’m making use of the gnu compilers and related tool chains, these tools are installed on the processor board(Freescale i.MX515) with Ubuntu. I make a connection to it from my host PC(Windows) using WinSCP and […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1019","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/1019","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=1019"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/1019\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=1019"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=1019"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=1019"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}as -o functions.o functions.s<\/code> and try running the generated functions.o<\/strong> using .\/functions.o<\/code> command, the bash shell is failing to recognize this file as an executable(on pressing tab functions.o is not getting selected\/PuTTY is not highlighting the file).<\/p>\nHelp, please!!!<\/h2>\n
ubuntu@ubuntu-desktop:~\/Documents\/Project\/Others\/helloworld$ make\ngcc -c -mcpu=cortex-a8 main.c\nas -mcpu=cortex-a8 -o functions.o functions.s\ngcc -o hello main.o functions.o\nfunctions.o: In function `_start':\n(.text+0x0): multiple definition of `_start'\n\/usr\/lib\/gcc\/arm-linux-gnueabi\/4.3.3\/..\/..\/..\/crt1.o:init.c:(.text+0x0): first defined here\ncollect2: ld returned 1 exit status\nmake: *** [hello] Error 1\n<\/code><\/pre>\n#include \n#include \n\nint main(void) {\n\n puts(\"!!!Hello World!!!\"); \/* prints !!!Hello World!!! *\/\n return EXIT_SUCCESS;\n}\n<\/code><\/pre>\n* Main program *\/\n .equ STACK_TOP, 0x20000800\n .text\n .global _start\n .syntax unified\n\n_start:\n .word STACK_TOP, start\n .type start, function\n\nstart:\n movs r0, #10\n movs r1, #0\n .end\n<\/code><\/pre>\nall: hello\n\nhello: main.o functions.o\n gcc hello -o main.o functions.o\n<\/code><\/pre>\nmain.o: main.c\n gcc -c -mcpu=cortex-a8 main.c\n\nfunctions.o: functions.s\n as -mcpu=cortex-a8 -o functions.o functions.s\n<\/code><\/pre>\nubuntu@ubuntu-desktop:~\/Documents\/Project\/Others\/helloworld$ make\ngcc -c -mcpu=cortex-a8 main.c\nas -mcpu=cortex-a8 -o functions.o functions.s\ngcc -o main.o functions.o\nfunctions.o: In function `_start':\n(.text+0x0): multiple definition of `_start'\n\/usr\/lib\/gcc\/arm-linux-gnueabi\/4.3.3\/..\/..\/..\/crt1.o:init.c:(.text+0x0): first defined here\n\/usr\/lib\/gcc\/arm-linux-gnueabi\/4.3.3\/..\/..\/..\/crt1.o: In function `_start':\ninit.c:(.text+0x30): undefined reference to `main'\ncollect2: ld returned 1 exit status\nmake: *** [hello] Error 1\n<\/code><\/pre>\n\n
hello: main.o functions.o\n gcc -o main.o functions.o\n<\/code><\/pre>\nhello: main.o functions.o\n gcc -o hello main.o functions.o\n<\/code><\/pre>\nhello: main.o functions.o\n gcc -o main.o functions.o\n<\/code><\/pre>\nhello: main.o functions.o\n gcc -o hello main.o functions.o\n<\/code><\/pre>\n<\/li>\ngcc -nostdlib -o hello main.o functions.o\n<\/code><\/pre>\n<\/li>\n