March 1999 - l4-hackers - example.com Site

"relocation truncated"
by edmundo＠rano.demon.co.uk 15 Mar '99

15 Mar '99

I wrote to Hohmuth about this, but he might be away or busy ... http://os.inf.tu-dresden.de/fiasco/faq.html#5992 says: [v0.5 981012] Build problem when building oskit/examples/multiboot-smp: "relocation truncated" I cannot reproduce this problem. However, as this binary isn't needed, you can work around this problem by "touch oskit/examples/multiboot-smp". (hohmuth 98/10/24) I got exactly this error when I tried building Fiasco. It was preceded by a warning coming from boot.S, which might be connected, so I'm copying the edited highlights below. Does anyone with knowledge of x86 assembler understand this problem, and can they fix it? How come it only affects some people? Is it caused by different versions of the assembler? Isn't the assembler part of gcc? I'm using standard gcc 2.7.2.3, so which other packages should I check the versions of? I'm using Debian's binutils version 2.9.1.0.19a-2, for example, as released with Debian 2.1. I got the same assembler warning several times when building L4-Linux. Edmund gcc -c -MD -DHAVE_CONFIG_H -I. -I../libsmp/x86 -I- -I.. -I.. -I../flux/c -nostdinc -DASSEMBLER -MD ../libsmp/x86/boot.S /tmp/cca03216: Assembler messages: /tmp/cca03216:538: Warning: warning: missing prefix `*' in absolute indirect address, maybe misassembled! ... ... ... ld -Ttext 100000 -L../lib \ -o multiboot-smp ../lib/multiboot.o multiboot-smp.o \ -lsmp -lkern -lmc -llmm ../lib/crtn.o ../lib/libsmp.a(boot.o): In function `_SMP_TRAMP_START_': boot.o(.text+0x29): relocation truncated to fit: R_386_16 _SMP_TRAMP_32_ENTRY_ make[2]: *** [multiboot-smp] Error 1 make[2]: Leaving directory `/usr/local/tmp/L4/l4/oskit/examples' make[1]: *** [examples/all.MAKE] Error 2 make[1]: Leaving directory `/usr/local/tmp/L4/l4/oskit' make: *** [oskit] Error 2

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send/receive confusion
by edmundo＠rano.demon.co.uk 15 Mar '99

15 Mar '99

Dear Hackers, I've been studying the descriptions of IPC in the L4 Reference Manual (x86) and the L4 User Manual (MIPS) and would be grateful if someone could confirm to me that I've correctly understood some points which are not explicitly stated in those manuals. Here's are my hypotheses/deductions; please tell me if I'm right or wrong! (1) Both the "send message descriptor" and the "receive message descriptor" allow in-line data, strings and fpages to be transmitted in both directions. In fact, the names are confusing and they might better be referred to as "client message descriptor" and "server message descriptor" as the only differences between them relate to the way the other party is addressed - plus one little optimisation for the case where a "receive message descriptor" wants to receive just an fpage. (2) If you want to transmit some data from thread S to thread T, one way of doing it is to get thread S to do a SEND operation and thread T to do a RECEIVE FROM operation, but you could equally well get thread S to do a RECEIVE FROM and thread T to do a SEND, as the "RECEIVE FROM" and "SEND" IPC types have nothing to do with "receive" and "send", really. (3) When you do a CALL operation, specifying both a "send message descriptor" and a "receive message descriptor" in the same system call, in most cases you probably only want to send data with the former and only receive data with the latter. Since both descriptors have space for both directions, you can use the same message descriptor as both send message descriptor and receive message descriptor, if you want. But you don't have to. Edmund

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Re: send/receive confusion
by gernot＠cse.unsw.edu.au 14 Mar '99

14 Mar '99

Edmundo, I think I now understand the source of your confusion. In the Intel version of the L4 manual (at least in my copy of Sep 96), on p25 where the "rcv descriptor" is explained, the option "mem" has the top 30 bits of the descriptor word as "*snd msg/4". That should, of course, read "*rcv msg/4". Also, further to what I wrote in my previous mail: GH> - one or more page mappings or grants, provided that GH> - the "m" bit is set in the send descriptor, and GH> - the beginning of the sender's direct string (starting with the GH> register part) contains at least one valid "send fpage", and GH> - the receive descriptor either has the form of a valid "receive GH> fpage", or points to a "message" struct containing a valid "receive GH> fpage", and GH> - there is no error The second last bullet should read: - the receive descriptor either has the form of a valid "receive fpage" and the "m" bit is set, or points to a "message" struct containing a valid "receive fpage", and Gernot -- Gernot Heiser ,--_|\ School of Computer Sci. & Engin. Phone: +61 2 9385 5156 / \ The University of NSW Fax: +61 2 9385 5995 \_,--._* Sydney, Australia 2052 E-mail: G.Heiser(a)unsw.edu.au v http://www.cse.unsw.edu.au/~gernot PGP fingerprint: 94 1E B8 28 25 FD 7C 94 20 10 92 E5 0B FF 39 8F

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implementations of L4
by Edmund GRIMLEY EVANS 12 Mar '99

12 Mar '99

I've been trying to find out about existing implementations of L4. Perhaps people could correct or add to what I have discovered: * The original L4 by Jochen Liedtke. Written in assebler. For i486 and i586. NOT FREE and therefore utterly useless :-) * L4/MIPS from Australia. Written in assembler? GNU. * L4/Alpha from Dresden and Australia. Written in assembler? Not yet released but probably GNU? * Fiasco from Dresden. Written in C++, and designed for portabilty rather than efficiency, but only runs on i486 and i586 at present. GNU. * A version of L4 for x86 from Dresden written in C. I saw this mentioned in the list archive. Is it really separate from Fiasco? * L4/ARM in assembler. Unfinished? I saw this in the archive, too. If this list could be corrected and completed, could it be put on the L4 website, with links, as it must be what a lot of casual readers are interested in knowing? Edmund

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486/Pentium version problems
by Edmund GRIMLEY EVANS 12 Mar '99

12 Mar '99

Following the instructions at os.inf.tu-dresden.de/fiasco/use.html I built Fiasco and the Hello World server worked. Excellent! Then I tried building L4-Linux and it didn't work ... Then I noticed that grub-ext2fs-floppy apparently already contains everything you need to run L4-Linux except for L4 itself. So I just copied the fiasco "main" that I had built onto the floppy image as supplied, hacked menu.lst a bit at random, and tried that. That didn't work either, but the thing that caught my attention was a message something like this: RMGR: L4/Pentium ... I was running this on a 486. So my questions are: Do the same executables (main, rmgr, sigma0, glinux.gz) run on both 486 and Pentium, or do different versions have to be built? If the latter, are the versions in grub-ext2fs-floppy supposed to work only on Pentium? If so, how can I build a version for 486 when compiling on a 686 machine? (And also, could the code be made to run on both? It would make life easier ...) Edmund

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