break point command Z0 not supported

["Manoj Verma, Noida" <manojv@noida.hcltech.com>]

Hi,
I am doing remote debugging using GDB server over ethernet. Both host and
target are i386-linux machines.

I am debugging a simple 'Hello World' application.

On the Gdb client side: 
(gdb) break main
(gdb) set debug remote 1
(gdb) continue

I see the following packet transaction (excerpt):

########################################################################
(gdb) c
Continuing.
Sending packet: $Z0,4000acb0,1#2d...Ack
Packet received: 
Packet Z0 (software-breakpoint) is NOT supported
Sending packet: $m4000acb0,1#e4...Ack
Packet received: 55
Sending packet: $M4000acb0,1:cc#c4...Ack
Packet received: OK
Sending packet: $m8048338,1#3c...Ack
Packet received: 83
Sending packet: $M8048338,1:cc#1c...Ack
Packet received: OK
...
...<Manoj: omitted non-releveant data >
...
Sending packet: $M4000acb0,1:55#68...Ack
Packet received: OK
Sending packet: $M8048338,1:83#c1...Ack
Packet received: OK
########################################################################

My questions are:
1) What does it mean by 'software-breakpoint is NOT supported'?
2) The gdb is reading data at some particular location (here 4000acb0 &
8048338)and inserting "cc" at that address. And at the end of 'continue'
response it replaces back the original data at that particular address. Is
this the standard way of GDB functioning?

Kindly clarify..

Thanks..