Gentoo Archives: gentoo-user

From: Richard Fish <bigfish@××××××××××.org>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] SegFault while compiling gcc 4.1.1
Date: Fri, 01 Dec 2006 04:45:18
In Reply to: Re: [gentoo-user] SegFault while compiling gcc 4.1.1 by "Vladimir G. Ivanovic"
1 On 11/30/06, Vladimir G. Ivanovic <vgivanovic@×××××××.net> wrote:
2 > I have done nothing to my hardware and I've seen this error, oh, a
3 > half a dozen times, the last time 3 months (?) ago. I ran memtest when
4 > I installed new memory, and it did not report problems even when run
5 > for hours.
7 memtest is basically useless these days. It can only tell you if you
8 have a bad memory cell, which almost never happens today. Most memory
9 problems are the result of timing issues between the processor(s) and
10 DMA controllers.
12 This script [1] seems to be a much better memory test for modern
13 systems, although you may have to make some tweaks to run it on
14 Gentoo.
16 > And I do not get random segfaults with other programs.
18 Yes, compiling is very unique in this regard. The memory access
19 pattern of a compiler, reading and writing to locations on different
20 rows, or even different modules, under high CPU load and using lots of
21 memory, with some IO thrown in for good measure, tends to reveal
22 hardware problems quite nicely.
24 > Finally, I don't think my hardware fixed itself.
25 >
26 > Given all of this, my suspicion is that these errors are software
27 > bugs, not hardware problems.
29 If we were talking about a driver, or an event-based GUI program, I
30 might agree. But a compiler is going to take the exact same actions
31 given the same input and options. The compiler isn't going to do
32 something different between 2 different executions over the _exact_
33 same sources because it feels like it.
35 >
36 > The other thing that I don't really believe is the part about "this
37 > bug not being reproducible" as reported by portage/emerge/make/gcc.
39 Then you should read the gcc sources. One of the patches applied by
40 Gentoo adds a retry loop when the compiler is about to exit with an
41 internal compiler error (ICE). It retries the compile twice, and if
42 either of those succeeds, you get the "The bug is not reproducible"
43 message. It doesn't output anything because that would possibly
44 obscure the original error.
46 The gentoo devs probably added this loop to avoid more duplicates of [2].
48 -Richard
50 [1]
51 [2]
52 --
53 gentoo-user@g.o mailing list


Subject Author
Re: [gentoo-user] SegFault while compiling gcc 4.1.1 "Vladimir G. Ivanovic" <vgivanovic@×××××××.net>