Hi, Some platforms, such as Blackfin, have a special prefix for assembly symbols as opposed to C symbols. For this reason, a function named "foo()" in C will in fact be visible as a symbol called "_foo" in the ELF binary.
The current linker version script logic in libgcc doesn't take into account this situation properly. The Blackfin specific libgcc/config/bfin/libgcc-glibc.ver has an additional "_" in front of every symbol so that it matches the output of "nm" (which gets parsed to produce the final linker version script). But due to this additional "_", ld no longer matches with the symbols since "ld" does the matching with the original symbol name, not the one prefixed with "_". Due to this, none of the symbols in libgcc/config/bfin/libgcc-glibc.ver are actually matched with symbols in libgcc. This causes all libgcc symbols to be left as "LOCAL", which causes lots of "undefined reference" whenever some C or C++ code that calls a function of libgcc is compiled. To address this, this commit introduces a "skip_underscore" variable to the mkmap-symver script. It tells mkmap-symver to ignore the leading underscore from the "nm" output. Note that this new argument is different from the existing "leading_underscore" argument, which *adds* an additional underscore to the generated linker version script. Having this functionality paves the way to using the generic linker version information for Blackfin, instead of using a custom one. Signed-off-by: Thomas Petazzoni <thomas.petazz...@free-electrons.com> Tested-by: Waldemar Brodkorb <w...@openadk.org> 2016-11-06 Thomas Petazzoni <thomas.petazz...@free-electrons.com> PR gcc/74748 * libgcc/mkmap-symver.awk: add support for skip_underscore diff --git a/libgcc/mkmap-symver.awk b/libgcc/mkmap-symver.awk index 266832a..30bb179 100644 --- a/libgcc/mkmap-symver.awk +++ b/libgcc/mkmap-symver.awk @@ -47,7 +47,11 @@ state == "nm" && ($1 == "U" || $2 == "U") { state == "nm" && NF == 3 { split ($3, s, "@") - def[s[1]] = 1; + if (skip_underscore) + symname = substr(s[1], 2); + else + symname = s[1]; + def[symname] = 1; sawsymbol = 1; next; } Thanks in advance, Waldemar