Hello,

What is the byte register name of esi?

Like dl is for edx

In OllyDbg

sil. That said, I thought that OllyDbg was 32-bit software and so couldn't access it directly.

there is no way to access it directly in 32bit code. only in 64bit code

...and in 64bit mode, you can only access the lowest part, right? (ie, no AH/BH/CH/DH).

yup

I would say "yup" to one interpretation of f0dder's question, which is to ask whether there is no 8-bit register corresponding to bits 8:15 of RSP/RBP/RSI/RDI.

I would say "nope" to another interpretation, which is to ask whether the AH/CH/DH/BH registers are not directly addressible in 64-bit mode.

That's a lot of negatives above, so let me summarize by saying that in 64-bit mode if an instruction has a REX prefix it may address registers al/cl/dl/bl/spl/bpl/sil/dil/r8l/r9l/r10l/r11l/r12l/r13l/r14l/r15l. If an instruction has no REX prefix it may address registers al/cl/dl/bl/ah/ch/dh/bh.

you are right, sorry.

Thanks for the clarification