How To Access Registers In Gdb

Meridian 5 Answer for How to print register values in GDB?

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info registers shows all the registers; info registers eax shows just the annals eax. The command can be abbreviated as i r

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If you lot're trying to print a specific annals in GDB, you have to omit the % sign. For case,

              info registers eip

If your executable is 64 fleck, the registers first with r. Starting them with e is not valid.

              info registers rip

Those tin can be abbreviated to:

              i r rip

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There is also:

              info all-registers

So you tin can get the register proper name you lot are interested in -- very useful for finding platform-specific registers (similar NEON Q... on ARM).

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If only want check it one time, info registers bear witness registers.
If only want scout 1 register, for example, display $esp proceed display esp registers in gdb control line.
If want watch all registers, layout regs go along show registers, with TUI mode.

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Gdb commands:

i r <register_name>: print a single annals, eastward.chiliad i r rax, i r eax
i r <register_name_1> <register_name_2> ...: print multiple registers, e.thou i r rdi rsi,
i r: impress all register except floating bespeak & vector annals (xmm, ymm, zmm).
i r a: print all register, include floating betoken & vector register (xmm, ymm, zmm).
i r f: print all FPU floating registers (st0-7 and a few other f*)

Other register groups besides a (all) and f (float) can exist establish with:

              maint print reggroups

every bit documented at: https://sourceware.org/gdb/current/onlinedocs/gdb/Registers.html#Registers

Tips:

xmm0 ~ xmm15, are 128 bits, about every modern auto has it, they are released in 1999.
ymm0 ~ ymm15, are 256 bits, new machine usually have information technology, they are released in 2011.
zmm0 ~ zmm31, are 512 bits, normal pc probably don't have it (every bit the year 2016), they are released in 2013, and mainly used in servers and then far.
Just one series of xmm / ymm / zmm will exist shown, because they are the same registers in different mode. On my machine ymm is shown.