Rappel: A REPL for x86, amd64, and armv7
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Rappel: A REPL for x86, amd64, and armv7
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Re: Rappel: A REPL for x86, amd64, and armv7
#2I was looking for something exactly like this a few months back.
Re: Rappel: A REPL for x86, amd64, and armv7
#3Cool! I did something very similar to this a couple of years back: https://github.com/osandov/asmase. Instead of assembling to a file, I used the LLVM libraries to assemble in memory, then used ptrace to get a child process to point its instruction pointer at that machine code.
Re: Rappel: A REPL for x86, amd64, and armv7
#4Cool. Like debug[0][1], but less functional? I could myself using this more if some of debug's features were implemented.
Re: Rappel: A REPL for x86, amd64, and armv7
#5This is cool. In the old days... computers came with these things built into the ROM (BIOS, Firmware, etc.). They were mostly called a 'ROM Monitor' or just the 'Monitor'. I never knew why they were called that, but I would guess that it was probably a term DEC or IBM invented.
On a Sun, NeXT, or Cisco box, you could hit a magic keyboard sequence (or send an RS-232 BREAK over the console) to get to the monitor. It was a very powerful thing to be able to interrupt the running OS, modify it, and then resume it. On the NeXT, you could even work with OS structures or sync the disks. The monitor typically had a disassembler and a simple single step debugger.
Earlier microcomputers also had these, and were helpful, but less powerful. For example, the Apple ][ had a monitor, but later ROMs did not allow you to invoke it with a key sequence.
On the later Suns and Power Macs, the monitor was implemented as a standard called Open Firmware. This was basically a standardized Forth acting as a Monitor. Device drivers could be embedded as a bytecode like sequence of Forth words for ethernet or display cards. That way, you could use newer devices even with old firmware and with any CPU. Very cool.
I wish this functionality would come back.
Re: Rappel: A REPL for x86, amd64, and armv7
#6I like how it colorized which registers have changed due to the last instruction.
Awesome!
Re: Rappel: A REPL for x86, amd64, and armv7
#7This is cool. In the old days... computers came with these things built into the ROM (BIOS, Firmware, etc.). They were mostly called a 'ROM Monitor' or just the 'Monitor'. I never knew why they were called that, but I would guess that it was probably a term DEC or IBM invented. On a Sun, NeXT, or Cisco box, you could hit a magic keyboard sequence (or send an RS-232 BREAK over the console) to get to the monitor. It wa…
On the old Sun gear if you sent a break signal over serial you wold interrupt the OS sure and be at the ROM monitor but you couldn't "resume" the OS, you could boot back up to single user or run level 3 but all of your previous state would be gone of course. Is that was you are referring to? I don't remember a disassembler being available from the prom monitor I do remember there a FORTH(sp?) interpreter though. Could you elaborate?
Re: Rappel: A REPL for x86, amd64, and armv7
#8This is cool. In the old days... computers came with these things built into the ROM (BIOS, Firmware, etc.). They were mostly called a 'ROM Monitor' or just the 'Monitor'. I never knew why they were called that, but I would guess that it was probably a term DEC or IBM invented. On a Sun, NeXT, or Cisco box, you could hit a magic keyboard sequence (or send an RS-232 BREAK over the console) to get to the monitor. It wa…
On the old Sun gear if you sent a break signal over serial you wold interrupt the OS sure and be at the ROM monitor but you couldn't "resume" the OS, you could boot back up to single user or run level 3 but all of your previous state would be gone of course. Is that was you are referring to? I don't remember a disassembler being available from the prom monitor I do remember there a FORTH(sp?) interpreter though. Coul…
The OpenFirmware system used on old Macintosh and Sun machines used an extended FORTH for the bootstrapping and hardware management. FreeBSD's bootloader has a similar system as well.
Re: Rappel: A REPL for x86, amd64, and armv7
#9This is cool. In the old days... computers came with these things built into the ROM (BIOS, Firmware, etc.). They were mostly called a 'ROM Monitor' or just the 'Monitor'. I never knew why they were called that, but I would guess that it was probably a term DEC or IBM invented. On a Sun, NeXT, or Cisco box, you could hit a magic keyboard sequence (or send an RS-232 BREAK over the console) to get to the monitor. It wa…
On the old Sun gear if you sent a break signal over serial you wold interrupt the OS sure and be at the ROM monitor but you couldn't "resume" the OS, you could boot back up to single user or run level 3 but all of your previous state would be gone of course. Is that was you are referring to? I don't remember a disassembler being available from the prom monitor I do remember there a FORTH(sp?) interpreter though. Coul…
There was a command to resume the OS after a break.
You just hit 'c' then enter.
http://www.cisco.com/c/en/us/support/docs/field-notices/misc...
Re: Rappel: A REPL for x86, amd64, and armv7
#10This is cool. In the old days... computers came with these things built into the ROM (BIOS, Firmware, etc.). They were mostly called a 'ROM Monitor' or just the 'Monitor'. I never knew why they were called that, but I would guess that it was probably a term DEC or IBM invented. On a Sun, NeXT, or Cisco box, you could hit a magic keyboard sequence (or send an RS-232 BREAK over the console) to get to the monitor. It wa…
"This is cool."
Not just cool, but useful. "UEFI" should have been a Forth-like REPL like Sun, FreeBSD, OLPC, etc.
The output of rappel reminds me of an "assembly level debugger" I used for many years called "ald". Maybe I am just stupid, but when I'm writing assembly I like to verify the contents of registers as a program executes.
From user.h: "Fuck computers, multiarch is bullshit."
Agreed.
I need something that compiles easily on NetFreeOpenBSD x86. Mo multiarch bullshit. Meanwhile I will stick with as, objcopy and ald.