Date: Mon, 10 May 2021 16:20:52 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 207898] kernel linker behaves differently on amd64 vs. i386 Message-ID: <bug-207898-227-sk7A721saU@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-207898-227@https.bugs.freebsd.org/bugzilla/> References: <bug-207898-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D207898 Justin Cady <desk@justincady.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |desk@justincady.com --- Comment #4 from Justin Cady <desk@justincady.com> --- > Why would the linker ignore the flag for local symbols? That seems like = it could be the source of difficult to debug problems. I have the same question, and I can confirm that such problems are very difficult to debug. :( In my case, Module-A, which depends on Modules B and C, is intended to pick= up a globally exported symbol from Module-B, but picks up a _local_ symbol of = the same name from Module-C (which happens to be scanned by the linker first). I believe that is because of this bug. I verified this was causing my issue by editing link_elf_lookup_symbol() in sys/kern/link_elf_obj.c to populate the sym pointer and return success only= if the symbol has global binding (STB_GLOBAL). With that change, the local sym= bol from Module-C is ignored, and the global symbol from Module-B is correctly selected. 1. Am I correct that because of this bug, symbol names on amd64 are effecti= vely required to be unique across all kernel module dependencies? 2. Is there any risk to actually fixing this? I tried to understand all of = the potential callers of link_elf_lookup_symbol(), but doing so is not straightforward through all the indirect calls (function pointers, macros). Stated differently: is there any expectation that link_elf_lookup_symbol() should return a local symbol? --=20 You are receiving this mail because: You are the assignee for the bug.=
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