topic Re: MPC5748G (cut2) Compare-and-Store via DMSC not working in MPC5xxx

MPC5748G (cut2) Compare-and-Store via DMSC not working

ali_taqweem — Thu, 09 Jul 2020 13:09:52 GMT

Hi,

I have been trying to use atomic Compare-and-Store DMSC instruction, but it gives machine check exception. Not able to with BUS_DRERR, MAV, G and LD set in MCSR. The address range is accessible (other DMSC operations are working I tried Load-and-set-1 (bit)). Here is the code that I am using:

foo:
    e_lis   r5, 0x9000                        ; Create decoration: cast.h, CD16 0
foo_lock:
    lhdcbx r4, r5, r3                          ; Atomic set resource, caching inhibited
    se_cmpi r4, 0x0
    e_bne- foo_lock
    se_blr                                      ; Return

Help shall be appreciated.

Re: MPC5748G (cut2) Compare-and-Store via DMSC not working

lukaszadrapa — Mon, 13 Jul 2020 12:04:06 GMT

Hi Ali,

the decoration information in r5 is not correct. It's not valid opcode, so machine check is triggered. You can find in the reference manual:

If I use opcode 0x6.... instead of 0x9..., the instruction is executed successfully.

Regards,

Lukas

Re: MPC5748G (cut2) Compare-and-Store via DMSC not working

ali_taqweem — Mon, 13 Jul 2020 12:09:54 GMT

Hi Lukas,

I think you misunderstood me. LAS1 (opcode 0x06) works on my side as well.

I want to use CAST (opcode 0x09), it give machine check.

Regards,
Ali

Re: MPC5748G (cut2) Compare-and-Store via DMSC not working

lukaszadrapa — Tue, 14 Jul 2020 05:28:27 GMT

CAST can be used with store instructions. lhdcbx is load instruction.

Regards,

Lukas