Date: Sun, 13 Mar 2016 22:50:56 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 207898] kernel linker behaves differently on amd64 vs. i386 Message-ID: <bug-207898-8-1i4IIOjM4k@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-207898-8@https.bugs.freebsd.org/bugzilla/> References: <bug-207898-8@https.bugs.freebsd.org/bugzilla/>
next in thread | previous in thread | raw e-mail | index | archive | help
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207898 Jilles Tjoelker <jilles@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jilles@FreeBSD.org --- Comment #2 from Jilles Tjoelker <jilles@FreeBSD.org> --- There is another MD aspect of the kernel linker: whether kernel modules are object files (file says "ELF xx-bit yyy relocatable") or DSOs (file says "ELF xx-bit yyy shared object"). Of the architectures you are looking at, i386 uses DSOs and amd64 uses object files. Using object files may reduce overhead slightly but bypasses functionality that may be useful. For example, DSOs have a symbol table for dynamic linking separate from the one for debugging, while object files only have a single symbol table. Although there is a flag for static (local) symbols, the kernel linker ignores it and some code may have started abusing this ignoring. Note that, although i386 kernel modules are DSOs, they are not PIC and do not use a GOT and PLT. Therefore, there is no overhead from the DSO format while running the code. -- You are receiving this mail because: You are the assignee for the bug.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-207898-8-1i4IIOjM4k>