Why gdb/gdbserver handler breakpoint on gdb client side (ARM)?

Hi.

Recently I am working on debugging a bug of gdb/gdbserver when setting
breakpoints on ARM devices. I found that, gdb-client nearly do nothing
about it when we use gdb/gdbserver on x86 platform, gdbserver do the
dirty work in fact, including generate INT 3 instruction, read, save,
and write memory, etc... But for ARM, this work is done on the
gdb-client side, which is opposed to x86 case. Anyone know why? Or any
thoughts?

Thanks.