Messages in this thread | | | Subject | Re: [PATCH 1/3] LoongArch: tools: Add relocs tool support | From | Xi Ruoyao <> | Date | Fri, 02 Sep 2022 19:10:25 +0800 |
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Hi Youling,
On Fri, 2022-09-02 at 18:08 +0800, Youling Tang wrote: > This tool is based on the arch/mips/boot/tools/relocs tool.
I've dig some history of MIPS relocatable kernel (https://lwn.net/Articles/682020/):
* Kernel is compiled & statically linked as normal, with no position independent code. MIPS before R6 only has limited relative jump instructions so the vast majority of jumps are absolute. To compile the kernel position independent would introduce a highly undesireable overhead. Relocating the static binary gives a small startup time penalty but the kernel otherwise perforns normally.
Unlike (pre-r6) MIPS, LoongArch has a complete support for PIC, and currently LoongArch toolchain always produces PIC (except, if -Wa,-mla- {local,global}-with-abs or la.abs macros are used explicitly).
So would it be easier to review and correct the uses of "la.abs" in the code, and make the main kernel image a real PIE? Then we can load it everywhere w/o any need to do relocation at load time.
-- Xi Ruoyao <xry111@xry111.site> School of Aerospace Science and Technology, Xidian University
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