binutils | 易学教程

How to set 2 byte wchar_t output?

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问题 The GCC uses a 4-byte wchar_t by default. I can set the option -fshort-wchar to get 2 bytes per wchar_t in the L"string constants" . But when I set the compiler option to my source file I get the famous warning message foo.o uses 2-byte wchar_t yet the output is to use 4-byte wchar_t ; use of wchar_t values across objects may fail Since I really want 2-byte wchar_t I also want the output to use this variant. Is there any linker option to tell it what I want? Edit This warning doesn't inhibit

gnu ld/gdb: separate debug files. How to produce the debug file when there's too much debug info to link?

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问题 There's now gdb and binutils support for separating debug info from the binaries to be debugged. Docs describing this can be found in: gdb: separate debug files objcopy --add-gnu-debuglink, --only-keep-debug ld --build-id After a bit of experimenting, I'm able to get gdb (7.6) to find the debug info using either the build-id and debug-link methods. Here's two gdb fragments that show the debugger finding the debug info in the non-standard locations, using the build-id and debug-link methods

Generating link-time error for deprecated functions

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问题 Is there a way with gcc and GNU binutils to mark some functions such that they will generate an error at link-time if used? My situation is that I have some library functions which I am not removing for the sake of compatibility with existing binaries, but I want to ensure that no newly-compiled binary tries to make use of the functions. I can't just use compile-time gcc attributes because the offending code is ignoring my headers and detecting the presence of the functions with a configure

Building a two-part firmware image using GCC toolchain

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问题 I have some firmware built with GCC that runs on an ARM Cortex M0 based microcontroller. The build currently generates a single binary image that can be written into the program memory of the microcontroller. For reasons to do with field update, I need to split this image into two parts that can be updated separately. I'll call these Core and App . Core : contains the interrupt vector table, main() routine, and various drivers and library routines. It will be located in the first half of the

Is there a way to unhide hidden-visibility symbols with GNU binutils?

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I'm working on a script to make uClibc usable on an existing glibc-targetted gcc/binutils toolchain, and the one problem I'm left with is that pthread_cancel needs to dlopen libgcc_s.so.1 . The version supplied with the host gcc is linked to depend on glibc, so I'm instead using ld 's -u option to pull in the needed symbols (and their dependencies) from libgcc_eh.a to make a replacement libgcc_s.so.1 : gcc -specs uclibc.specs -Wl,-u,_Unwind_Resume -Wl,-u,__gcc_personality_v0 \ -Wl,-u,_Unwind_ForcedUnwind -Wl,-u,_Unwind_GetCFA -shared -o libgcc_s.so.1 In principle I would be done, but all the

android NDK: objcopy --rename-sym does not work (need to rename a function in a .so file)

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问题 I cannot get objcopy --rename-sym working. In a new Android project, I have created the directory jni and the file stub.c: #include <jni.h> #include "dlog.h" jint JNI_OnLoad(JavaVM* vm, void* reserved) { DLOG("~~~~~~~~~~~~~~~~~~~~~~~ JNI_OnLoad ~~~~~~~~~~~~~~~~~~~~~~~~~"); return JNI_VERSION_1_6; } int myfunc() { return 0; } the command ~/an/ndk-build -j 4 says: [armeabi-v7a] Install : libTest.so => libs/armeabi-v7a/libTest.so [armeabi] Install : libTest.so => libs/armeabi/libTest.so [x86]

How to decide the base address for the location counter “.” when VMA and LMA are different?

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According to the ld manual on the special symbol . , i.e.the Location Counter . Note: . actually refers to the byte offset from the start of the current containing object. Normally this is the SECTIONS statement, whose start address is 0, hence . can be used as an absolute address. If . is used inside a section description however, it refers to the byte offset from the start of that section, not an absolute address. Thus in a script like this: SECTIONS { . = 0x100 .text: { *(.text) . = 0x200 } . = 0x500 .data: { *(.data) . += 0x600 } } The '.text' section will be assigned a starting address of

objdump and ARM vs Thumb

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问题 I'm trying to disassemble an object built for ARM with gcc. Unfortunately, objdump is trying to guess whether the code is ARM and Thumb, and is getting it wrong: it thinks my code is Thumb when it's actually ARM. I see that objdump has an option to force it to interpret all instructions as Thumb ( -Mforce-thumb ), but it doesn't have one to force ARM mode! This seems like a really weird omission to me, and it's seriously hampering my ability to get work done (I'm on an embedded device and my

gnu ld/gdb: separate debug files. How to produce the debug file when there's too much debug info to link?

阅读更多关于 gnu ld/gdb: separate debug files. How to produce the debug file when there's too much debug info to link?

There's now gdb and binutils support for separating debug info from the binaries to be debugged. Docs describing this can be found in: gdb: separate debug files objcopy --add-gnu-debuglink, --only-keep-debug ld --build-id After a bit of experimenting, I'm able to get gdb (7.6) to find the debug info using either the build-id and debug-link methods. Here's two gdb fragments that show the debugger finding the debug info in the non-standard locations, using the build-id and debug-link methods respectively: (gdb) set debug-file-directory . (gdb) file uWithBuildId Reading symbols from /home/peeterj

How to set 2 byte wchar_t output?

阅读更多关于 How to set 2 byte wchar_t output?

The GCC uses a 4-byte wchar_t by default. I can set the option -fshort-wchar to get 2 bytes per wchar_t in the L"string constants" . But when I set the compiler option to my source file I get the famous warning message foo.o uses 2-byte wchar_t yet the output is to use 4-byte wchar_t ; use of wchar_t values across objects may fail Since I really want 2-byte wchar_t I also want the output to use this variant. Is there any linker option to tell it what I want? Edit This warning doesn't inhibit the linker to produce a valid output. But the dozens of false warnings cover other messages. In