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

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Fri, 22 Jul 2005, vamsi krishna wrote:

> Hello,
>
>>
>> The location of the vsyscall page is different on 32 and 64 bit
>> machines. So 0xffffe000 is NOT the address you are looking for while
>> dealing with the 64 bit machine.  Rather 0xffffffffff600000 is the
>> correct location (on x86-64).
>>
> Both my process's are 32-bit process's, its just one runs on 64-bit
> machine and other runs on 32-bit machine. The write from address
> 0xffffe0000 to a file on a 32-bit machine fails, but does'nt fail on
> 64-bit machine (the process is still 32-bit although it runs on
> 64-bit).
>
> How can the virtual address of   0xffffffffff600000 exist in a 32-bit
> process ? (May be I have not made myself clear in explaining the
> problem?? :-?)
>
> Best,
> Vamsi.

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


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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