Re: llvm/sparc64: match BFD -N alignment

> Date: Tue, 18 Aug 2026 15:18:01 +0200
> From: "Kirill A. Korinsky" <[email protected]>
> 
> Robert, Sebastien,
> 
> BFD aligns nonpaged PT_LOAD segments to their maximum contained section
> alignment. Do the same for SPARCV9 instead of retaining the 1 MiB maximum
> page alignment.
> 
> This removes roughly 1 MiB of leading padding from ofwboot without changing
> its load address or memory layout.
> 
> Here diff for the base and llvm/22 in ports.
> 
> Ok?

This is questionable.  What problem are you trying to solve?

> Index: src/gnu/llvm/lld/ELF/Driver.cpp
> ===================================================================
> RCS file: /home/cvs/src/gnu/llvm/lld/ELF/Driver.cpp,v
> diff -u -p -r1.25 Driver.cpp
> --- src/gnu/llvm/lld/ELF/Driver.cpp	30 Jul 2026 19:28:37 -0000	1.25
> +++ src/gnu/llvm/lld/ELF/Driver.cpp	18 Aug 2026 13:01:23 -0000
> @@ -3496,6 +3496,12 @@ template <class ELFT> void LinkerDriver:
>    // sections are non-aligned (maxPageSize set to 1) but text sections are aligned
>    // to the target page size.
>    ctx.arg.textAlignPageSize = ctx.arg.omagic ? getRealMaxPageSize(ctx, args) : ctx.arg.maxPageSize;
> +#ifdef __OpenBSD__
> +  // Match BFD -N semantics for SPARCV9: use the maximum contained section
> +  // alignment for PT_LOAD segments instead of the 1 MiB page alignment.
> +  if (ctx.arg.omagic && ctx.arg.emachine == EM_SPARCV9)
> +    ctx.arg.textAlignPageSize = ctx.arg.maxPageSize;
> +#endif
>  
>    ctx.arg.imageBase = getImageBase(ctx, args);
>  
> Index: src/gnu/llvm/lld/ELF/Writer.cpp
> ===================================================================
> RCS file: /home/cvs/src/gnu/llvm/lld/ELF/Writer.cpp,v
> diff -u -p -r1.11 Writer.cpp
> --- src/gnu/llvm/lld/ELF/Writer.cpp	30 Jul 2026 19:28:37 -0000	1.11
> +++ src/gnu/llvm/lld/ELF/Writer.cpp	18 Aug 2026 13:01:23 -0000
> @@ -2701,6 +2701,16 @@ template <class ELFT> void Writer<ELFT>:
>    ctx.out.programHeaders->offset = ctx.out.elfHeader->size;
>    uint64_t off = ctx.out.elfHeader->size + ctx.out.programHeaders->size;
>  
> +#ifdef __OpenBSD__
> +  // BFD's implicit script reserves 0x200 bytes before fixed-address SPARCV9
> +  // -N payloads consumed by OpenFirmware.
> +  if (!ctx.arg.relocatable && ctx.arg.omagic &&
> +      ctx.arg.emachine == EM_SPARCV9 &&
> +      ctx.arg.sectionStartMap.count(".text") &&
> +      !ctx.script->hasSectionsCommand && !ctx.script->hasPhdrsCommands())
> +    off = std::max<uint64_t>(off, 0x200);
> +#endif
> +
>    PhdrEntry *lastRX = nullptr;
>    for (Partition &part : ctx.partitions)
>      for (auto &p : part.phdrs)
> Index: ports/devel/llvm/22/Makefile
> ===================================================================
> RCS file: /home/cvs/ports/devel/llvm/22/Makefile,v
> diff -u -p -r1.22 Makefile
> --- ports/devel/llvm/22/Makefile	30 Jul 2026 19:28:03 -0000	1.22
> +++ ports/devel/llvm/22/Makefile	18 Aug 2026 13:17:33 -0000
> @@ -2,7 +2,7 @@ LLVM_MAJOR =	22
>  LLVM_VERSION =	${LLVM_MAJOR}.1.8
>  LLVM_PKGSPEC =	>=22,<23
>  
> -REVISION =	4
> +REVISION =	5
>  
>  SHARED_LIBS +=	LLVM		0.0 \
>  		LTO		0.0 \
> Index: ports/devel/llvm/22/patches/patch-lld_ELF_Driver_cpp
> ===================================================================
> RCS file: /home/cvs/ports/devel/llvm/22/patches/patch-lld_ELF_Driver_cpp,v
> diff -u -p -r1.3 patch-lld_ELF_Driver_cpp
> --- ports/devel/llvm/22/patches/patch-lld_ELF_Driver_cpp	30 Jul 2026 19:28:03 -0000	1.3
> +++ ports/devel/llvm/22/patches/patch-lld_ELF_Driver_cpp	18 Aug 2026 13:14:56 -0000
> @@ -169,7 +169,7 @@ Index: lld/ELF/Driver.cpp
>   // Parses --image-base option.
>   static std::optional<uint64_t> getImageBase(Ctx &ctx, opt::InputArgList &args) {
>     // Because we are using `ctx.arg.maxPageSize` here, this function has to be
> -@@ -3435,6 +3491,11 @@ template <class ELFT> void LinkerDriver::link(opt::Inp
> +@@ -3435,6 +3491,17 @@ template <class ELFT> void LinkerDriver::link(opt::Inp
>     // optimizations such as DATA_SEGMENT_ALIGN in linker scripts. LLD's use of it
>     // is limited to writing trap instructions on the last executable segment.
>     ctx.arg.commonPageSize = getCommonPageSize(ctx, args);
> @@ -178,6 +178,12 @@ Index: lld/ELF/Driver.cpp
>  +  // sections are non-aligned (maxPageSize set to 1) but text sections are aligned
>  +  // to the target page size.
>  +  ctx.arg.textAlignPageSize = ctx.arg.omagic ? getRealMaxPageSize(ctx, args) : ctx.arg.maxPageSize;
> ++#ifdef __OpenBSD__
> ++  // Match BFD -N semantics for SPARCV9: use the maximum contained section
> ++  // alignment for PT_LOAD segments instead of the 1 MiB page alignment.
> ++  if (ctx.arg.omagic && ctx.arg.emachine == EM_SPARCV9)
> ++    ctx.arg.textAlignPageSize = ctx.arg.maxPageSize;
> ++#endif
>   
>     ctx.arg.imageBase = getImageBase(ctx, args);
>   
> Index: ports/devel/llvm/22/patches/patch-lld_ELF_Writer_cpp
> ===================================================================
> RCS file: /home/cvs/ports/devel/llvm/22/patches/patch-lld_ELF_Writer_cpp,v
> diff -u -p -r1.2 patch-lld_ELF_Writer_cpp
> --- ports/devel/llvm/22/patches/patch-lld_ELF_Writer_cpp	30 Jul 2026 19:28:03 -0000	1.2
> +++ ports/devel/llvm/22/patches/patch-lld_ELF_Writer_cpp	18 Aug 2026 13:14:56 -0000
> @@ -183,11 +183,10 @@ Index: lld/ELF/Writer.cpp
>     if (OutputSection *cmd = findSection(ctx, ".note.gnu.property", partNo))
>       addHdr(PT_GNU_PROPERTY, PF_R)->add(cmd);
>   
> -@@ -2586,6 +2610,31 @@ template <class ELFT> void Writer<ELFT>::fixSectionAli
> -         };
> +@@ -2587,6 +2611,31 @@ template <class ELFT> void Writer<ELFT>::fixSectionAli
>       }
>     };
> -+
> + 
>  +#ifndef __OpenBSD__
>  +  // On i386, produce binaries that are compatible with our W^X implementation
>  +  if (ctx.arg.emachine == EM_386) {
> @@ -212,6 +211,24 @@ Index: lld/ELF/Writer.cpp
>  +    }
>  +  }
>  +#endif
> - 
> ++
>     for (Partition &part : ctx.partitions) {
>       prev = nullptr;
> +     for (auto &p : part.phdrs)
> +@@ -2651,6 +2700,16 @@ static std::string rangeToString(uint64_t addr, uint64
> + template <class ELFT> void Writer<ELFT>::assignFileOffsets() {
> +   ctx.out.programHeaders->offset = ctx.out.elfHeader->size;
> +   uint64_t off = ctx.out.elfHeader->size + ctx.out.programHeaders->size;
> ++
> ++#ifdef __OpenBSD__
> ++  // BFD's implicit script reserves 0x200 bytes before fixed-address SPARCV9
> ++  // -N payloads consumed by OpenFirmware.
> ++  if (!ctx.arg.relocatable && ctx.arg.omagic &&
> ++      ctx.arg.emachine == EM_SPARCV9 &&
> ++      ctx.arg.sectionStartMap.count(".text") &&
> ++      !ctx.script->hasSectionsCommand && !ctx.script->hasPhdrsCommands())
> ++    off = std::max<uint64_t>(off, 0x200);
> ++#endif
> + 
> +   PhdrEntry *lastRX = nullptr;
> +   for (Partition &part : ctx.partitions)
> 
> 
> 
> -- 
> wbr, Kirill
> 
>