runtime: remove commented out code from ARM Linux boot

The code was commented out by https://golang.org/cl/13234050 in 2013.
Let's just remove it.

Change-Id: I46ae1f07386719e991458e782d236214c40bdce1
Reviewed-on: https://go-review.googlesource.com/70770
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

diff --git a/src/runtime/rt0_linux_arm.s b/src/runtime/rt0_linux_arm.s
index 597e642adb717786958c31c945c180fec869d1b2..b56ec750711a4d37863e88ddf9dd8e5c47ed2284 100644 (file)
--- a/src/runtime/rt0_linux_arm.s
+++ b/src/runtime/rt0_linux_arm.s
@@ -93,76 +93,20 @@ GLOBL _rt0_arm_linux_lib_argv<>(SB),NOPTR,$4
 
 TEXT _rt0_arm_linux1(SB),NOSPLIT,$-4
        // We first need to detect the kernel ABI, and warn the user
-       // if the system only supports OABI
+       // if the system only supports OABI.
        // The strategy here is to call some EABI syscall to see if
        // SIGILL is received.
-       // To catch SIGILL, we have to first setup sigaction, this is
-       // a chicken-and-egg problem, because we can't do syscall if
-       // we don't know the kernel ABI... Oh, not really, we can do
-       // syscall in Thumb mode.
+       // If you get a SIGILL here, you have the wrong kernel.
 
        // Save argc and argv
        MOVM.DB.W [R0-R1], (R13)
 
-       // Thumb mode OABI check disabled because there are some
-       // EABI systems that do not support Thumb execution.
-       // We can run on them except for this check!
-
-       // // set up sa_handler
-       // MOVW $bad_abi<>(SB), R0 // sa_handler
-       // MOVW $0, R1 // sa_flags
-       // MOVW $0, R2 // sa_restorer
-       // MOVW $0, R3 // sa_mask
-       // MOVM.DB.W [R0-R3], (R13)
-       // MOVW $4, R0 // SIGILL
-       // MOVW R13, R1 // sa
-       // SUB  $16, R13
-       // MOVW R13, R2 // old_sa
-       // MOVW $8, R3 // c
-       // MOVW $174, R7 // sys_sigaction
-       // BL   oabi_syscall<>(SB)
-
        // do an EABI syscall
        MOVW    $20, R7 // sys_getpid
        SWI     $0 // this will trigger SIGILL on OABI systems
        
-       // MOVW $4, R0  // SIGILL
-       // MOVW R13, R1 // sa
-       // MOVW $0, R2 // old_sa
-       // MOVW $8, R3 // c
-       // MOVW $174, R7 // sys_sigaction
-       // SWI  $0 // restore signal handler
-       // ADD  $32, R13
-
        B       runtime·rt0_go(SB)
 
-TEXT bad_abi<>(SB),NOSPLIT,$-4
-       // give diagnosis and exit
-       MOVW    $2, R0 // stderr
-       MOVW    $bad_abi_msg(SB), R1 // data
-       MOVW    $45, R2 // len
-       MOVW    $4, R7 // sys_write
-       BL      oabi_syscall<>(SB)
-       MOVW    $1, R0
-       MOVW    $1, R7 // sys_exit
-       BL      oabi_syscall<>(SB)
-       B       0(PC)
-
-DATA bad_abi_msg+0x00(SB)/8, $"This pro"
-DATA bad_abi_msg+0x08(SB)/8, $"gram can"
-DATA bad_abi_msg+0x10(SB)/8, $" only be"
-DATA bad_abi_msg+0x18(SB)/8, $" run on "
-DATA bad_abi_msg+0x20(SB)/8, $"EABI ker"
-DATA bad_abi_msg+0x28(SB)/4, $"nels"
-DATA bad_abi_msg+0x2c(SB)/1, $0xa
-GLOBL bad_abi_msg(SB), RODATA, $45
-
-TEXT oabi_syscall<>(SB),NOSPLIT,$-4
-       ADD $1, R15, R4 // R15 is hardware PC
-       WORD $0xe12fff14 //BX   (R4) // enter thumb mode
-       // TODO(minux): only supports little-endian CPUs
-       WORD $0x4770df01 // swi $1; bx lr
-
 TEXT main(SB),NOSPLIT,$-4
        MOVW    $_rt0_arm_linux1(SB), R4
        B               (R4)