Re: a small C program to test xdm's /dev/mem reading on your architecture
on my pc164lx running woody 2.4.18 kernel with 512M mem.
read #1022 of 16384 bytes
read #1023 of 16384 bytes
read #1024 of 16384 bytes
done with read of /dev/mem (returned 1).
sumFile() succeeded.
ganesha:~# cat /proc/cpuinfo
cpu : Alpha
cpu model : EV56
cpu variation : 7
cpu revision : 0
cpu serial number :
system type : EB164
system variation : LX164
system revision : 0
system serial number :
cycle frequency [Hz] : 533333333
timer frequency [Hz] : 1024.00
page size [bytes] : 8192
phys. address bits : 40
max. addr. space # : 127
BogoMIPS : 1057.24
kernel unaligned acc : 0 (pc=0,va=0)
user unaligned acc : 0 (pc=0,va=0)
platform string : Digital AlphaPC 164LX 533 MHz
cpus detected : 1
on my pc164ux woody 2.4.18 kernel, 512M memory, same result
cpu : Alpha
cpu model : EV56
cpu variation : 0
cpu revision : 0
cpu serial number : Linux_is_Great!
system type : Ruffian
system variation : 0
system revision : 0
system serial number : MILO-/aux/KERNE
cycle frequency [Hz] : 600000000
timer frequency [Hz] : 1024.00
page size [bytes] : 8192
phys. address bits : 40
max. addr. space # : 127
BogoMIPS : 1187.96
kernel unaligned acc : 0 (pc=0,va=0)
user unaligned acc : 0 (pc=0,va=0)
platform string : N/A
cpus detected : 0
On Mon, 26 Aug 2002 01:20:33 -0500
Branden Robinson <branden@debian.org> wrote:
> The long story, for those interested:
>
> http://lists.debian.org/debian-x/2002/debian-x-200208/msg00091.html
>
> (and read the whole thread)
>
> The short story:
>
> I need people with root on machines of your given architecture to
> compile and run the attached C program. It consists of code borrowed
> from xdm's genauth.c program.
>
> The X Strike Force is trying to determine for which architectures it's a
> bad idea to read several megabytes of data sequentially from /dev/mem,
> because this is exactly what XDM currently does when generating an
> XDM-AUTHORIZATION-1 cookie.
>
> Be warned: on at least some architectures (notably IA-64), this sort of
> read has been known to cause untrapped machine checks (a.k.a., lockups
> or spontaneous reboots). Arguably the kernel should trap this sort of
> nonsense, so you may be in the mood to file a bug against "kernel" after
> running this program.
>
> I and the other folks at the X Strike Force need to know the following
> things:
>
> 1) whether or not this program works when you run it without arguments
> 2) if scenario 1) causes problems, what the last line of output was
> 3) if scenario 1) causes problems, whether invoking this program with
> the argument "fragile" helps it
> 4) if scenario 3) causes problems, what the last line of output was
>
> Remember, this program must be run as root. If normal users can read
> from /dev/mem on your machine, you're in trouble. :)
>
> --
> G. Branden Robinson | No math genius, eh? Then
> perhaps Debian GNU/Linux | you could explain to me
> where you branden@debian.org | got these...
> PENROSE TILES! http://people.debian.org/~branden/ | -- Stephen R.
> Notley
>
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