[Level2] Pass parameters to make.

$ cat Makefile
all:
ifdef aa
        echo "defined"
ifeq "${aa}" "123"
        echo "true"
else
        echo "false"
endif
else
        echo "not defined"
endif
$

$ make

echo "not defined"

not defined

$

$ make aa="000"

echo "defined"

defined

echo "false"

false

$

$ make aa="123"

echo "defined"

defined

echo "true"

true

$

Wish this helps.
 regards,
Stanley Huang