Question: Memory change request

Question: Memory change request

[Leslie Donaldson]

Hello,
  I realise this may be a little off topic but I think the kernel is the
only
place I will be able to pull this stunt.

I need a block of memory that can notify me or even a flag set when
it has been written to. I was thinking of letting the user code generate
some sort of page fault... Any random thoughts would be greatly
appreciated.

mmm ... Basically dirty page logic for user space....

Leslie Donaldson

-- 
/----------------------------\ Current Contractor: None
|    Leslie F. Donaldson     | Current Customer  : None
|    Computer Contractor     | Skills:
Unix/OS9/VMS/Linux/SUN-OS/C/C++/assembly
| Have Computer will travel. | WWW  :
http://www.cs.rose-hulman.edu/~donaldlf
\----------------------------/ Email: mail://donaldlf@cs.rose-hulman.edu
Goth Code V1.1: GoCS$$ TYg(T6,T9) B11Bk!^1 C6b-- P0(1,7) M+ a24 n---
b++:+
                H6'11" g m---- w+ r+++ D--~!% h+ s10 k+++ R-- Ssw
LusCA++
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

Re: Question: Memory change request

[Chris Wedgwood]

On Wed, Jan 24, 2001 at 12:44:58AM -0600, Leslie Donaldson wrote:

    I need a block of memory that can notify me or even a flag set when
    it has been written to. I was thinking of letting the user code generate
    some sort of page fault... Any random thoughts would be greatly
    appreciated.
    
    mmm ... Basically dirty page logic for user space....

mprotect the page(s) you are interested in so you can't write to them
and catch SEGV -- when someone attempts to write you can pull apart
the stack frame mark the page(s) RO and continue.

if you are really stuck i think i have example code to do this
somewhere for ia32 (stack frame is arch. dependent)


  --cw


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

RE: Question: Memory change request

[David Schwartz]

> mprotect the page(s) you are interested in so you can't write to them
> and catch SEGV -- when someone attempts to write you can pull apart
> the stack frame mark the page(s) RO and continue.
> 
> if you are really stuck i think i have example code to do this
> somewhere for ia32 (stack frame is arch. dependent)

	I bet ElectricFence would serve as example code.

	DS

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

Re: Question: Memory change request

[Chris Wedgwood]

On Wed, Jan 24, 2001 at 12:47:53AM -0800, David Schwartz wrote:
    	I bet ElectricFence would serve as example code.

don't think so.. it doesn't handle pulling the stack frame apart and
continuation


  --cw

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

Re: Question: Memory change request

[Jamie Lokier]

Leslie Donaldson wrote:
> I need a block of memory that can notify me or even a flag set when
> it has been written to. I was thinking of letting the user code generate
> some sort of page fault... Any random thoughts would be greatly
> appreciated.

Look for the Boehm garbage collector.  It has code for handling and
recovering from dirty page faults.

-- Jamie
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/