On Thu, Sep 5, 2024 at 5:10 PM Andrew Cooper <andrew.coop...@citrix.com> wrote:
> On 05/09/2024 4:42 pm, Jan Beulich wrote: > > On 05.09.2024 15:06, Andrew Cooper wrote: > >> --- a/xen/arch/x86/efi/efi-boot.h > >> +++ b/xen/arch/x86/efi/efi-boot.h > >> @@ -102,9 +102,6 @@ static void __init efi_arch_relocate_image(unsigned > long delta) > >> } > >> } > >> > >> -extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[]; > >> -extern const s32 __trampoline_seg_start[], __trampoline_seg_stop[]; > > I'd prefer if these stayed here, leaving the 4 symbols as minimally > exposed as > > possible. Recall that efi-boot.h isn't really a header in that sense, but > > rather a .c file. Elsewhere we keep decls in .c files when they're used > in just > > one CU. > > See Frediano's RFC series, which needs to change this in order to move > the 32bit relocation logic from asm to C. > > Not strictly necessary, I can declare in the C file as they were declared in efi-boot.h (which is more a .c file as an header as Jan said). I think the idea of declaring into a source file is that if another file wants to use it has to declare it again, so a bit more friction. But any access to trampoline variables should be considered as something to limit in any case, so having in a separate header helps (this does not mean that removing from the header is still increasing the friction). Personally, I'm not strong about the 2 options here. Slightly prefer having all variable declared in a single header. The only reason efi-boot.h can get away with this right now is because > the other logic is written entirely in asm. > > > Scope-limiting linker section boundaries more than regular variables is > weird to me. It's not as if they magically take more care to use than > regular variables, and trampoline.h is not a wide scope by any means. > > Frediano
