how to r/w memory

how to r/w memory

[loody]

Dear all:
From the gdb document, we can use "x/nfu address" to read memory, but
how we can write it?
I have tried "x 0x80000000=0" like "p var=val" but it fail.
thanks for your help,
miloody

Re: how to r/w memory

[Paul Pluzhnikov]

On Mon, Jun 15, 2009 at 10:47 PM, loody<miloody@gmail.com> wrote:

> From the gdb document, we can use "x/nfu address" to read memory, but
> how we can write it?

I usually do:
  (gdb) set *(int *)0x80000000 = 0

If GDB knows has debug info associated with the memory location,
  (gdb) print var = 2
or
  (gdb) set var = 3
also work for me.

If GDB knows the symbol, but doesn't have debug info for it, you'll have
to do cast again:
  (gdb) set *(int *)&var = 4

Cheers,
-- 
Paul Pluzhnikov

Re: how to r/w memory

[Alfred M. Szmidt]

One can also use the `restore' command (and its friends to dump memory
regions to a file), see (gdb) Dump/Restore Files for further
information.

Re: how to r/w memory

[André Pönitz]

On Tuesday 16 June 2009 07:47:50 loody wrote:
> Dear all:
> From the gdb document, we can use "x/nfu address" to read memory, but
> how we can write it?
> I have tried "x 0x80000000=0" like "p var=val" but it fail.
> thanks for your help,
> miloody

I use 

  set {char[5]} &buffer = {65,66,67,68,69}

I am not sure it's the recommended approach but "works".

Andre'

Re: how to r/w memory

[loody]

Hi:

2009/6/16 André Pönitz <andre.poenitz@nokia.com>:
> On Tuesday 16 June 2009 07:47:50 loody wrote:
>> Dear all:
>> From the gdb document, we can use "x/nfu address" to read memory, but
>> how we can write it?
>> I have tried "x 0x80000000=0" like "p var=val" but it fail.
>> thanks for your help,
>> miloody
>
> I use
>
>  set {char[5]} &buffer = {65,66,67,68,69}
>
> I am not sure it's the recommended approach but "works".
thanks for your help.
BTW, when checking the usage of breakpoint.
It seems 2 kinds of them, HW and SW.
What are the differences?
appreciate your help,
miloody