On Thu, Jul 13, 2006 at 10:45:34AM +0200, Peter S. Mazinger wrote: > On Wed, 12 Jul 2006, Vivek Goyal wrote: > > > On Mon, Jun 26, 2006 at 03:20:53PM -0700, Ian Lance Taylor wrote: > > > Amit Gud <[EMAIL PROTECTED]> writes: > > > > > > > I'm compiling the GNU/Linux kernel as a shared library and I've found > > > > that relocation entries are created even for absolute symbols. Is > > > > there any work-around for this, or is it a known bug? > > > > > > That is correct behaviour if the symbol is globally visible. In a > > > shared library, by default, any symbol may be overridden by the main > > > executable. That means that a relocation entry is required. > > > > > > > I am compiling my kernel with option --pic-executable to ld. As per ld > > man page, symbols defined in the executable can not be overriden. Still > > I see the relocation entries of type R_386_32 for absolute symbols. > > Wouldn't you also need -fPIE|-fpie in CFLAGS (that breaks the build > though) >
I do not want to generate position independent code and I am ok with text relocations as unlike normal shared libraries, text segment of kernel is not supposed to be shared. Hence not specifying -fPIE in CFLAGS. I just want to generate relocation entries of type R_386_RELATIVE in fully linked kernel so that at load time I can relocate it by some offset say X. Currently kernel compiles and loads at physical address 1MB (i386, x86_64). At load time I want to load it at a different physical address say 16MB. While loading I shall process all the relocations (Ideally which should just be of type R_386_RELATIVE, as there are no external symbol references and I am not generating a position independent code). Everything else seems to be ok if I link with option "-pie -Bsymbolic" except the fact that relocations of type R_386_RELATIVE are being generated for absolute symbols. Thanks Vivek > Peter > > > > c0100018 00003e01 R_386_32 c0412000 __bss_start > > c010001d 00003601 R_386_32 c04d7768 __bss_stop > > c0100064 00004901 R_386_32 c04d8000 pg0 > > c0100848 00004501 R_386_32 c03dc040 jiffies > > > > If absolute symbols are not to be relocated then why is linker generating > > relocation entries. > > > > Then I used options "--pic-executable -Bsymbolic". In this case > > also linker generated relocation entries for absolute sysmbols. Only > > difference was that relocation type was R_386_RELATIVE and linker > > had already processed the relocations for absolute sysmbols. > > > > c0100018 00000008 R_386_RELATIVE > > > > Addr c0100018 belongs to absolute symbol referece (_bss_start) in code. > > > > In this case if absolute symbols relocation have already been processed > > and absolute symbols have no more to be relocated then why > > a R_386_RELATIVE entry is being generated. > > > > My basic goal is to build dynamically relocatable kernel. I thought that > > I can use the relocation information and relocate the kernel. But the > > relocation entries generated for absolute symbols as shown above spoil > > the whole approach. > > > > Is it a bug? or expected behaviour? > > > > Thanks > > Vivek > > > > -- > Peter S. Mazinger <ps dot m at gmx dot net> ID: 0xA5F059F2 > Key fingerprint = 92A4 31E1 56BC 3D5A 2D08 BB6E C389 975E A5F0 59F2 _______________________________________________ bug-binutils mailing list bug-binutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-binutils
