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Re: Help needed to track down bug: linking Linux kernel with gold creates unbootable kernel
On Thu, 2010-04-22 at 14:21 -0700, H.J. Lu wrote:
> On Thu, Apr 22, 2010 at 2:10 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> > On Mon, Apr 12, 2010 at 10:27 PM, Ian Lance Taylor <iant@google.com>
> wrote:
> >> John Reiser <jreiser@bitwagon.com> writes:
> >>
> >>> The differing .p_align values of 0x1000 vs 0x200000 indicate that
> >>> gold has a bug interpreting the commands from the linker script
> >>> for alignment of Elf64_Phdr.
> >>
> >> It is perhaps worth noting that for x86_64 gold by default uses -z
> >> max-page-size 0x1000 whereas the default for GNU ld is -z
> >> max-page-size 0x200000. While I haven't looked at the Linux linker
> >> script, perhaps it is assuming the latter.
> >>
> >
> > Linux kernel linker scripts needs to align .rodata section to 2MB:
> >
> > . = ALIGN((1 << 21));
> >
> > Since gold can only align to 4K, gold can't be used on Linux
> > kernel.
> >
>
> Hi Ian,
>
> If gold should be compatible with ld, this patch should be applied.
>
We can also workaround in the kernel by overriding the value with "-z
max-page-size=0x200000" if this is supported.
thanks,
suresh
>
> --
> H.J.
> ---
> diff --git a/gold/x86_64.cc b/gold/x86_64.cc
> index 9110278..99be4de 100644
> --- a/gold/x86_64.cc
> +++ b/gold/x86_64.cc
> @@ -516,7 +516,7 @@ const Target::Target_info
> Target_x86_64::x86_64_info =
> '\0', // wrap_char
> "/lib/ld64.so.1", // program interpreter
> 0x400000, // default_text_segment_address
> - 0x1000, // abi_pagesize (overridable by -z max-page-size)
> + 0x200000, // abi_pagesize (overridable by -z max-page-size)
> 0x1000, // common_pagesize (overridable by -z common-page-size)
> elfcpp::SHN_UNDEF, // small_common_shndx
> elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx