On Sat, Apr 04, 2020 at 02:59:16PM -0700, Nathan Chancellor wrote:
> On Sat, Apr 04, 2020 at 09:15:31PM +0800, Jiaxun Yang wrote:
> > On Fri, 3 Apr 2020 18:32:04 -0700
> > Fangrui Song <maskray@google.com> wrote:
> > 
> > > 
> > > Reproduce for a clang/lld developer:
> > > 
> > > make -j$(nproc) ARCH=mips CC=clang CROSS_COMPILE=mipsel-linux-gnu-
> > > LD=ld.lld O=/tmp/out/mipsel distclean malta_defconfig vmlinux
> > > (Requires mipsel-linux-gnu-as and clang in PATH)
> > > 
> > > I have noticed multiple problems.
> > > 
> > > % file .tmp_vmlinux.kallsyms1
> > > .tmp_vmlinux.kallsyms1: ELF 32-bit LSB executable, MIPS, MIPS32 rel2
> > > version 1 (SYSV), statically linked,
> > > BuildID[sha1]=ff348ad92c80e525b3f14149e57e8987de66e041, not stripped
> > > 
> > > In arch/mips/kernel/vmlinux.lds.S, VMLINUX_LOAD_ADDRESS (from load-y)
> > > is 0xffffffff8010000. GNU ld seems to allow 64-bit addresses when
> > > linking an ELFCLASS32 file. The addresses will be truncated to
> > > 32-bit. This behavior seems error-prone to me.
> > > 
> > > lld does the right thing by erroring out. I do notice a display
> > > problem of lld -Map and I have a patch to address that:
> > > https://reviews.llvm.org/D77445
> > > 
> > > For 32-bit linux-mips, the right approach seems to be make
> > > VMLINUX_LOAD_ADDRESS fit into 32-bit. However, my Linux-fu and
> > > MIPS-fu is not strong enough to do this :/
> > 
> > Hi MaskRay,
> > 
> > Could you please try this?
> > 
> > --- a/arch/mips/mti-malta/Platform
> > +++ b/arch/mips/mti-malta/Platform
> > @@ -6,6 +6,10 @@ cflags-$(CONFIG_MIPS_MALTA)    +=
> > -I$(srctree)/arch/mips/include/asm/mach-malta ifdef CONFIG_KVM_GUEST
> >      load-$(CONFIG_MIPS_MALTA)  += 0x0000000040100000
> >  else
> > +ifdef CONFIG_64BIT
> >      load-$(CONFIG_MIPS_MALTA)  += 0xffffffff80100000
> > +else
> > +    load-$(CONFIG_MIPS_MALTA)  += 0x80100000
> > +endif
> >  endif
> >  all-$(CONFIG_MIPS_MALTA)       := $(COMPRESSION_FNAME).bin
> > 
> > Thanks.
> > 
> > --
> > Jiaxun Yang
> 
> Thank you, that fixes the error and I see no new ones. I tested
> malta_defconfig, which boots in QEMU:
> 
> Linux version 5.6.0-next-20200404-dirty (nathan@ubuntu-m2-xlarge-x86) (ClangBuiltLinux clang version 11.0.0 (git://github.com/llvm/llvm-project 1ce0bc39eebe95a350174eb0ed4e2508e7cb6ed8), LLD 11.0.0 (git://github.com/llvm/llvm-project 1ce0bc39eebe95a350174eb0ed4e2508e7cb6ed8)) #1 SMP Sat Apr 4 14:54:45 MST 2020
> 
> Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Hi all, want to consult, does it mean 0-day ci doesn't need blacklist
this ld.lld error anymore? This is a kernel problem and the error itself
is valid.