| 1 | If Coro causes segfaults a lot on calls to libc functions, the cause is |
1 | If Coro causes segfaults a lot on calls to libc functions, the cause is |
| 2 | probably a glibc compiled for i386 and kernel 2.2. |
2 | probably a glibc compiled for i386 and kernel 2.2 (for example, debian |
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3 | only supplies 2.2 and 2.6-optimized libraries, not 2.4). |
| 3 | |
4 | |
| 4 | Glibc contains a bug that causes any program linked against pthreads AND |
5 | Glibc contains a bug that causes any program linked against pthreads AND |
| 5 | using coroutines (of any kind, not only Coro, but including most userspace |
6 | using coroutines (of any kind, not only Coro, but including most userspace |
| 6 | thread libraries like gnu-pth) or alternate stacks to segfault on calls to |
7 | thread libraries like gnu-pth) or alternate stacks to segfault on calls to |
| 7 | pthread functions. And glibc happens to do a lot of these calls. |
8 | pthread functions. And glibc happens to do a lot of these calls. |
| 8 | |
9 | |
| 9 | (Even if you pelr is not compiled against pthreads, Time::HiRes links |
10 | (Even if you perl is not compiled against pthreads, Time::HiRes links |
| 10 | against -lrt, which drags in pthreads. The same is true for other modules, |
11 | against -lrt, which drags in pthreads. The same is true for other modules, |
| 11 | so watch out). |
12 | so watch out). |
| 12 | |
13 | |
| 13 | The bug is rather difficult to fix. This is not a problem, however, since |
14 | The bug is rather difficult to fix. This is not a problem, however, since |
| 14 | glibcs compiled for linux-2.4 use a much more efficient method to locate |
15 | glibcs compiled for linux-2.4 use a much more efficient method to locate |
| 15 | their data, which happens to work with coroutines. |
16 | their data, which happens to work with coroutines. |
| 16 | |
17 | |
| 17 | So the easy fix is to install a libc which was compiled for linux-2.4, |
18 | So the easy fix is to install a libc which was compiled for linux-2.4 (or |
| 18 | using the "--enable-kernel=2.4 i586-pc-linux-gnu" configure options. |
19 | 2.6) using the "--enable-kernel=2.4 i586-pc-linux-gnu" configure options. |
| 19 | |
20 | |
| 20 | WARNING: This libc will no longer run on linux-2.2 or lower! |
21 | WARNING: This libc will no longer run on linux-2.2 or lower! |
| 21 | |
22 | |
| 22 | UPDATE: I am no longer able to compile glibc-2.3.2 in this way. The reason |
23 | UPDATE: Time::HiRes in current perl snapshots does no longer link against |
| 23 | is most probably that the glibc folks work on an enhanced thread local |
24 | -lrt. That still means you need to patch it until 5.9.x gets out. |
| 24 | storage facility, and it might be that you need a 2.5 or 2.6 kernel to |
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| 25 | make it work. Glibc-2.3.1 works fine, though. |
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