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Altera_Forum's avatar
Altera_Forum
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20 years ago

Building net-snmp for uClinux in FLT format

Hi all. I'm trying to build net-snmp for Nios II uClinux (specifically its agent, snmpd). I found an account of how to do this from forum member "temex" at http://forum.niosforum.com/forum/index.php?showtopic=2955 (http://forum.niosforum.com/forum/index.php?showtopic=2955) (see post# 5 in that topic)), but I seem to be missing the final step and I'm hoping someone here can help.

I downloaded the same version of net-snmp mentioned by temex (5.2.2), but I don't have the (expensive) Microtronix Nios II Linux CDK, so I downloaded what appears to be a very similar thing from http://scorpius.homelinux.org/~marc/nios2.html (http://scorpius.homelinux.org/~marc/nios2.html) (see "binary snapshot of the toolchain", near the bottom of that page). I installed that on a Linux PC and then followed the instructions from temex to build net-snmp for Nios II Linux, which went fine. However, the binaries that it produced were in the ELF format, and uClinux only accepts FLT.

So, my problem is: "what do I have to do to get FLT binaries?"

I&#39;ve already tried one approach. I&#39;ve got the Microtronix Nios II Linux Distribution 1.4 on a Windows PC (which has Quartus II 5.1 and the Nios II Development Kit 5.0), so I tried looking at what its tools do to make FLT binaries. In the Rules.mak for a Nios II Linux Application Project, it uses a program called elf2flt to do this, but when I tried to use that program on the ELF binary that I&#39;d made for snmpd, it died complaining that "Input file contains no relocation info". I noticed that the Rules.mak file used some linker options that might be needed to make elf2flt work on the resulting ELF file (it uses -r, -d, -Ur, and -T <a particular linker script>), so I tried making the net-snmp build process use those options by giving --with-ldflags="..." to ./configure. (I had to leave out -d because, when I supplied it, ./configure complained that nios2-linux-gcc couldn&#39;t make executables and wouldn&#39;t proceed.) However, when I built with these extra flags and tried to convert the ELFs, elf2flt still died with the same complaint. This seems odd to me, because the -r flag means to make a relocatable file, which is what elf2flt was demanding. I think the resulting ELF files might have been the same size as before, too ...

So ... does anyone know what I&#39;ve done wrong? http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif

Thanks in advance.

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    20 years ago

    It is a problem of gcc check in configure.

    You could add a short dummy --with-ldflag for configure only, eg, "-Wl,-v".

    After it build Makefile, edit the LDFLAGS in Makefile to include -elf2flt.
  • Altera_Forum's avatar
    Altera_Forum
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    20 years ago

    Awesome. After doing that, the binaries that the build made were in the FLT format. Thanks very much!

    To anyone else looking to get net-snmp&#39;s snmpd to work, I also needed to configure my kernel to support large mem allocations (Processor type and features -> Allow allocating large blocks of memory), and I need to run snmpd with -f. After that just set up the environment on your uClinux system like how snmpd needs it (i.e. with the .conf and the MIBs) and it runs fine.
  • Altera_Forum's avatar
    Altera_Forum
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    20 years ago

    Thanks hippo, I&#39;m going to try out the buildroot toolchain. I&#39;ll let you know how it goes.

    About net-snmp, if anyone needs to port 5.3.0.1, you can use the same procedure as for 5.2.2, except I also needed to comment out the definitions of getutent, endutent, and setutent in agent/mibgroup/host/hr_system.c (they&#39;re already defined in uClibc and the linker complains about having two sets of them). Also, if you use the same toolchain binaries as I did, then gcc&#39;s optimizer will introduce a bug when compiling agent/mibgroup/hardware/cpu/cpu.c. Either add &#39;asm("nop");&#39; after the call to _cpu_update_stats on line 34, or compile with -O1 instead of -O2.

    Incidentally, I&#39;ve also found that it&#39;s not necessary to use --with-ldflags="-Wl,-v" and then edit the Makefiles to add -elf2flt. You can just use --with-ldflags="-elf2flt" when running ./configure.
  • Altera_Forum's avatar
    Altera_Forum
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    19 years ago

    tschmelcher,

    how big did your executable get?

    When I build it , the snmpd has 1636952 Bytes.

    Is this approx right ?

    Is there a way to make it leaner?