[swift-dev] Failed to launch REPL process

Ron Olson tachoknight at gmail.com
Tue Oct 24 12:19:34 CDT 2017

Hi Alex-

Thanks for the info, but this isn't in a Docker container, just a 
regular Linux VM.

As an additional bit of info, I ran the build script on my Fedora 
laptop, and it works just fine; the REPL starts right up. I'd be 
surprised and confused if this was truly a VM (in this case, VMware 
ESXi) issue, but stranger things have happened I guess.


On 24 Oct 2017, at 12:11, Alex Blewitt wrote:

>> On 24 Oct 2017, at 17:00, Ron Olson via swift-dev 
>> <swift-dev at swift.org> wrote:
>> Hi all-
>> I am able to build Swift 4 on Fedora 26 Linux 
>> (https://github.com/tachoknight/swift-rpm) and while it can compile 
>> and run Swift code just fine, the REPL does not start because of:
>> error: failed to launch REPL process: process launch failed: 'A' 
>> packet returned an error: -1
> This occurs when you are running the docker image without a 
> --privileged flag, or without a --cap-add=SYS_PTRACE flag. You are not 
> able to debug any running program, and since the Swift REPL is 
> implemented as a front-end to an lldb debugging instance, it follows 
> that the Swift REPL will not work without the container being launched 
> without either of those flags.
> Alex

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