Actual result:
[    0.000000] Linux version 2.6.37.6 (peter@penguin) (gcc version 4.6.3 20120201 (prerelease) (Linaro GCC 4.6-2012.02) ) #12 Tue Mar 27 23:09:00 CEST 2012
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU revision is: 00018448 (MIPS 4KEc)
[    0.000000] TI AR7 (TNETD7300), ID: 0x0005, Revision: 0x26
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 02000000 @ 14000000 (usable)
[    0.000000] end of print_memory_map
[    0.000000] After print_memory_map
[    0.000000] boot_command_line 9428cca8 builtin_cmdline ffffff21 COMMAND_LINE_SIZE 4096

Expected:
[    0.000000] boot_command_line 9428cca8 builtin_cmdline 9428ff20 COMMAND_LINE_SIZE 4096


Modified source from http://lxr.linux.no/#linux+v2.6.37.6/arch/mips/kernel/setup.c#L463
        pr_info("Determined physical RAM map:\n");
        print_memory_map();

        pr_info("After print_memory_map\n");
#ifdef CONFIG_CMDLINE_BOOL
        pr_info("boot_command_line %p builtin_cmdline %p COMMAND_LINE_SIZE %zu\n", boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
        pr_info("builtin_cmdline[0] = %c\n", builtin_cmdline[0]);
#ifdef CONFIG_CMDLINE_OVERRIDE
        strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
#else
        if (builtin_cmdline[0]) {
                pr_info("before first strlcat\n");
                strlcat(arcs_cmdline, " ", COMMAND_LINE_SIZE);
                pr_info("Before second strlcat\n");
                strlcat(arcs_cmdline, builtin_cmdline, COMMAND_LINE_SIZE);
        }   
        pr_info("Before strlcpy\n");
        strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
#endif
        pr_info("%s", boot_command_line);
#else
        strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
#endif
        pr_info("Before boot_command_line strlcpy\n");
        strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);


Assembly
; pr_info("Determined physical RAM map:\n");
9427515c:       3c049423        lui     a0,0x9423
94275160:       0d0860f5        jal     0x942183d4
94275164:       2484021c        addiu   a0,a0,540

; print_memory_map();
94275168:       0d09d3ad        jal     0x94274eb4      ; print_memory_map
9427516c:       00000000        nop    

; pr_info("After print_memory_map\n");
94275170:       3c049423        lui     a0,0x9423
94275174:       0d0860f5        jal     0x942183d4      ; printk 
94275178:       24840240        addiu   a0,a0,576       ; "<6>After print_memory_map\n"

; pr_info("boot_command_line %p builtin_cmdline %p COMMAND_LINE_SIZE %zu\n", boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
9427517c:       3c049423        lui     a0,0x9423
94275180:       2484025c        addiu   a0,a0,604       ; "<6>boot_command_line %p builtin_cmdline %p COMMAND_LINE_SIZE %zu\n"
94275184:       2625cca8        addiu   a1,s1,-13144    ; 0x9428cca8 allocated memory for use
94275188:       2606ff20        addiu   a2,s0,-224      ; 0x9428ff20 "console=ttyS0,115200 console=ttyS1,115200"
9427518c:       0d0860f5        jal     0x942183d4      ; printk
94275190:       24071000        li      a3,4096         ; 4096