Re: [Qemu-devel] [PATCH v3] configure: Simplify alternate .text segment

[Richard Henderson <rth@twiddle.net>]

Ping 2.

On 07/02/2013 08:12 AM, Richard Henderson wrote:
> Ping.
> 
> On 06/21/2013 07:10 PM, Richard Henderson wrote:
>> For bsd-user and linux-user emulation modes QEMU needs to be linked at an
>> alternate .text segment address, so that it's out of the way of the guest
>> executable.  Instead of including modified linker scripts for each arch,
>> just set the address with -Ttext-segment if supported, or by using sed to
>> edit the default linker script.
>>
>> Cc: Ed Maste <emaste@freebsd.org>
>> Signed-off-by: Richard Henderson <rth@twiddle.net>
>> ---
>>  configure | 48 +++++++++++++++++++++++++++++++-----------------
>>  2 files changed, 31 insertions(+), 18 deletions(-)
>> --
>>
>> Changes v2-v3:
>>   * Move the check for textseg_ldflags much earlier in the configure file,
>>     so that we've not got cflags invalid for configure time.  Plus, the
>>     check (and generated ld script) only gets done once, not once per
>>     target directory.
>>   * Remove ia64 from the hosts that get relocation
>>   * Handle s390x like s390.
>>
>> Tested on x86_64, arm, hppa (old binutils needing config-host.ld),
>> sparc64, and ia64.  All various versions of linux.
>>
>>
>> r~
>>
>>
>>
>> diff --git a/configure b/configure
>> index ad32f87..63da418 100755
>> --- a/configure
>> +++ b/configure
>> @@ -3444,6 +3444,36 @@ if test "$cpu" = "s390x" ; then
>>    roms="$roms s390-ccw"
>>  fi
>>  
>> +# Probe for the need for relocating the user-only binary.
>> +if test "$pie" = "no" ; then
>> +  textseg_addr=
>> +  case "$cpu" in
>> +    arm | hppa | i386 | m68k | ppc | ppc64 | s390* | sparc | sparc64 | x86_64)
>> +      textseg_addr=0x60000000
>> +      ;;
>> +    mips)
>> +      textseg_addr=0x400000
>> +      ;;
>> +  esac
>> +  if [ -n "$textseg_addr" ]; then
>> +    cat > $TMPC <<EOF
>> +    int main(void) { return 0; }
>> +EOF
>> +    textseg_ldflags="-Wl,-Ttext-segment=$textseg_addr"
>> +    if ! compile_prog "" "$textseg_ldflags"; then
>> +      # In case ld does not support -Ttext-segment, edit the default linker
>> +      # script via sed to set the .text start addr.  This is needed on FreeBSD
>> +      # at least.
>> +      $ld --verbose | sed \
>> +        -e '1,/==================================================/d' \
>> +        -e '/==================================================/,$d' \
>> +        -e "s/[.] = [0-9a-fx]* [+] SIZEOF_HEADERS/. = $textseg_addr + SIZEOF_HEADERS/" \
>> +        -e "s/__executable_start = [0-9a-fx]*/__executable_start = $textseg_addr/" > config-host.ld
>> +      textseg_ldflags="-Wl,-T../config-host.ld"
>> +    fi
>> +  fi
>> +fi
>> +
>>  # add pixman flags after all config tests are done
>>  QEMU_CFLAGS="$QEMU_CFLAGS $pixman_cflags $fdt_cflags"
>>  libs_softmmu="$libs_softmmu $pixman_libs"
>> @@ -4072,9 +4102,6 @@ if test "$gcov" = "yes" ; then
>>    echo "GCOV=$gcov_tool" >> $config_host_mak
>>  fi
>>  
>> -# generate list of library paths for linker script
>> -$ld --verbose -v 2> /dev/null | grep SEARCH_DIR > config-host.ld
>> -
>>  # use included Linux headers
>>  if test "$linux" = "yes" ; then
>>    mkdir -p linux-headers
>> @@ -4437,21 +4464,8 @@ if test "$gprof" = "yes" ; then
>>    fi
>>  fi
>>  
>> -if test "$ARCH" = "tci"; then
>> -  linker_script=""
>> -else
>> -  linker_script="-Wl,-T../config-host.ld -Wl,-T,\$(SRC_PATH)/ldscripts/\$(ARCH).ld"
>> -fi
>> -
>>  if test "$target_linux_user" = "yes" -o "$target_bsd_user" = "yes" ; then
>> -  case "$ARCH" in
>> -  alpha | s390x | aarch64)
>> -    # The default placement of the application is fine.
>> -    ;;
>> -  *)
>> -    ldflags="$linker_script $ldflags"
>> -    ;;
>> -  esac
>> +  ldflags="$ldflags $textseg_ldflags"
>>  fi
>>  
>>  echo "LDFLAGS+=$ldflags" >> $config_target_mak
>>
>