On Fri, May 23, 2003 at 07:32:49AM +0200, Marc-Christian Petersen wrote:
> nono, this fix is the right one. All works fine :-)
Nope, the ioperm fix seems to be breaking something alright. Eventually
I was able to reproduce this on 2.5.69-mm[78] as well.
Here's my distilled test case. (My real test case is FCE Ultra, compiled
for svgalib. The crash happens in svgalib, version 1.4.3-cl1 if that
matters.)
---cut here---
#include <sys/io.h>
int main()
{
char c;
if (ioperm(0x3b4, 0x3df - 0x3b4 + 1, 1)) {
perror("ugh");
exit(1);
} else printf("ioperm succeeded\n");
printf("About to perform inb...\n");
c = inb(0x3cc);
printf("result: %d\n", (int)c);
return 0;
}
---cut here---
Steps to reproduce:
1. Compile this program (e.g., "gcc iopt.c" or "gcc -O2 iopt.c").
2. Switch to a text virtual console.
3. Log in as root (or log in as a normal user and su to root). This
program does not crash from within X, nor does it crash from an SSH
session.
4. Run the program (e.g., "./a.out").
5. The program will probably crash after "About to perfrom inb" but
before "result:...". If not, try it again a few times. If it still
doesn't crash for you, try logging in on another virtual console, or
just wait a few minutes and try again. Sometimes it's 10% reproducible
and sometimes it's well over 90% reproducible...
6. Examine the code/core using gdb. Notice that the inb caused the
segfault.
The real-world effect of this bug is that my NES emulator just broke
almost completely. :( Interestingly, a somewhat reliable workaround for
fceu (but not for my test case AFAICT) is to strace it rather than
running it directly -- then it usually doesn't segfault.
-Barry K. Nathan <barryn@pobox.com>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri May 23 2003 - 22:00:53 EST