Boosts welcome!

Anyone got any good primers on ARMv5TE assembly? Anything I should be learning beforehand?

I’m trying to target the MT1939 optical drive chipset in particular, which is what the MT1959 largely appears to be based on. MediaTek reports the MT1959 is ARM7EJ-S, if that makes a difference.

@maddy ARM7 isn't ARMv7... ARM7EJ-S is ARMv5TE: https://en.wikipedia.org/wiki/ARM7 (edit: originally this post said it was ARMv3, which is true for the original ARM7 but not ARM7EJ-S)

@noisytoot Oops! Thank you for this - I am not very knowledgeable yet, so this helps a lot.

@maddy

Avin might be able to help

@zarlez

@maddy @noisytoot I find it just hilarious that ISA and processor naming is like this - what would we do without entities like Noisytoot to translate the alphabet soup for us 😄

@maddy oooh is that the one with funky 28 bit pointers or whatever it is?

@cinebox I’m not actually sure - a lot of this is new to me, and I’m attempting to do what I can to learn.

Also if you have any experience reverse engineering optical drive firmwares and would be willing to lend a hand in helping me figure this out, I’d be eternally grateful, and willing to return the favour to others in the future.

@maddy yeah I’m just going off what I learned on Wikipedia

The Gameboy Advance used an ARMv3 CPU, you might be able to find some resources in the homebrew scene there

@cinebox Ooh, good call - thank you! 💜

@eestileib @maddy Oh yeah I work at Arm, but v3 is old so all my documentation stuff I don't know where guides might be for that stuff. If you have any specific questions though, ask me and I might be able to find an answer.

@zarlez @eestileib Thank you!!!

@maddy Sorry, I got it wrong. I reread the Wikipedia article and apparently ARM7EJ-S specifically implements ARM5vTE (but the original ARM7 was ARMv3, which is why I thought it was that)

@seabass @maddy at least it’s not RISC-V with its rv64imafdcbv_zic64b_zicbom_zicbop_zicboz_ziccamoa_ziccif_zicclsm_ziccrse_zicntr_zicond_zicsr_zifencei_zihintntl_zihintpause_zihpm_zimop_zmmul_za64rs_zaamo_zalrsc_zawrs_zfa_zfhmin_zca_zcb_zcd_zcmop_zba_zbb_zbs_zkt_zvbb_zve32f_zve32x_zve64d_zve64f_zve64x_zvfhmin_zvkb_zvkt_zvl128b_zvl32b_zvl64b_supm

@noisytoot @seabass Goodness.

@noisytoot All good - thank you for the correction! ^.^

@zarlez @eestileib Another mutual corrected themselves - they thought ARM7EJ-S was ARMv3, but they corrected and said it’s actually ARMv5TE if that changes anything!

@maddy @eestileib Hmm documentation implies actually Arm7 https://developer.arm.com/documentation/ddi0214/b/introduction/arm7ej-s-processor-architecture?lang=en

Which means this might be helpful? https://developer.arm.com/documentation/den0013/0400/Introduction-to-Assembly-Language?lang=en

@zarlez @eestileib I will read up! Thank you so much! ^.^