On 03/10/10 18:10, Albert ARIBAUD wrote: > Le 03/10/2010 01:07, Graeme Russ a écrit : >> On 03/10/10 08:09, Albert ARIBAUD wrote: >>> Le 02/10/2010 22:39, Reinhard Meyer a écrit : >>> >>>> And as an idea, if position independent code is used, only pointers >>>> in initialized data need adjustment. Cannot the linker emit a table >>>> of addresses that need fixing? >>> >>> IIU Bill C, yes the linker can emit the information and the startup code >>> could use this information instead of relying on hand-provided info; the >>> linker file probably needs to be modified in order to provide such info. >>> I intend to look into this, but feel free to do too. >> >> As mentioned previously, I have already done this for x86. The linker >> flags >> used are -pic and --emit-relocs. The linker produces a section named >> rel.dyn which needs to be processed but not loaded into RAM. rel.dyn >> contains a simple list of address (within .text, .data, .rodata etc) each >> of which need a simple adjustment equal to the relocation offset. > > Bill just said that -pic (or, for ARM, -fPIC or -fPIE) was unnecessary > for relocation. You seem to imply it actually is... In my experience, > -fPIC and-fPIE do increase code by adding GOT relocation to symbols that > need fixing, so they would indeed be redundant to any other relocation > mechanism -- I just did some test with basic code and this seems to > confirm, no -fPIx is needed to get relocation the way you do on ARM. >
Just to clarify -fpic is a compiler option, -pic is a linker option. x86 has no compile time relocation options (therefore no referencing .got etc). Using the link time pic option produces the relocation data table (.rel.dyn) which must be pre-processed before execution can begin at the relocated address Cheers, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
