On Fri, 2022-08-05 at 12:01 +0800, Lulu Cheng wrote: > > 在 2022/8/5 上午11:45, Xi Ruoyao 写道: > > > > > > On Fri, 2022-08-05 at 11:34 +0800, Xi Ruoyao via Gcc-patches wrote: > > > > > > > > > > > > > Or maybe we should just use a PC-relative addressing with 4 instructions > > > instead of GOT for -fno-PIC? > > Not possible, Glibc does not support R_LARCH_PCALA* relocations in > > ld.so. So we still need a -mno-got (or something) option to disable GOT > > for special cases like the kernel. > > > > > > > > > > > > > Both way consumes 16 bytes (4 instructions > > > for PC-relative, 2 instructions and a 64-bit GOT entry for GOT) and PC- > > > relative may be more cache friendly. But such a major change cannot be > > > backported for 12.2 IMO. > > > > > I'm very sorry, my understanding of the precpu variable is wrong, > I just read the code of the kernel you submitted, this precpu variable > not only has a large offset but also has an uncertain address when compiling, > so no matter whether it is addressed with pcrel Still got addressing needs > dynamic relocation when loading. It seems that accessing through the got table > is a better choice. > > The name movable is also very vivid to describe this function in the kernel, > indicating that the address of the variable can be changed at will. > > But this name is more difficult to understand in gcc, I have no opinion on > other, > can this name be changed?
Yes, we don't need to be compatible with old vendor compiler IMO. "force_got_access" as Xuerui suggested? -- Xi Ruoyao <xry...@xry111.site> School of Aerospace Science and Technology, Xidian University
