Re: Whats in this vaddr segment 0xffffe000-0xfffff000 ---p ?

[vamsi krishna <vamsi.krishnak@gmail.com>]

Really appreciate that, is roland mcgrath listening? what's his email ID?

On 7/23/05, linux-os (Dick Johnson) <linux-os@analogic.com> wrote:
> 
> On Fri, 22 Jul 2005, vamsi krishna wrote:
> 
> > Hi,
> >
> >> It doesn't. The 32-bit machines never show 64 bit words in
> >> /proc/NN/maps. They don't "know" how.
> >>
> >> b7fd6000-b7fd7000 rw-p b7fd6000 00:00 0
> >> b7ff5000-b7ff6000 rw-p b7ff5000 00:00 0
> >> bffe1000-bfff6000 rw-p bffe1000 00:00 0          [stack]
> >> ffffe000-fffff000 ---p 00000000 00:00 0          [vdso]
> >> ^^^^^^^^____________ 32 bits
> >
> > hello john can you tell me what is [vdso], does it have any content
> > related file descriptor table it seems that the if I dont save this
> > segment during checkpointing,  the file open descriptors (i.e FILE *)
> > seems to have null after restoration.
> >
> > Sincerely appreciate your inputs.
> >
> > Cheers!
> > Vamsi
> >
> 
> #include <stdio.h>
> 
> int main()
> {
>      long *foo = (long *)0xffffe000;
>      printf("%08x\n", foo[0]);
>      printf("%08x\n", foo[1]);
>      printf("%08x\n", foo[2]);
>      printf("%08x\n", foo[3]);
>      printf("%08x\n", foo[4]);
>      printf("%s\n", (char *)foo);
> 
> }
> 
> Seems to be readable and starts with 'ELF'. It's something
> the the 'C' runtime may library use to make syscalls to the
> kernel. Older libraries used interrupt 0x80, newer ones
> may use this. Roland McGrath has made patches to this
> segment so maybe he knows.
> 
> 
> 
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
> Warning : 98.36% of all statistics are fiction.
> .
> I apologize for the following. I tried to kill it with the above dot :
> 
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>