Re: status of Linux ptrace on amd64?

[christos%astron.com@localhost (Christos Zoulas)]

In article <20141201172756.GA29051@neva>,
Alexander Nasonov  <alnsn%yandex.ru@localhost> wrote:
>Hi,
>
>While trying to make some Linux instrumentation tool work on -current
>amd64 I noticed that ptrace support in compat_linux and compat_linux32
>have some notable differences and compat_linux32 has a better support.
>For instance, I can debug 32bit Linux binaries with NetBSD's gdb but
>any attempt to set a breakpoint on 64bit Linux results in SIGTRAP.
>
>Neither compat_linux32 nor compat_linux work for that particular tool
>because they don't support LIUNX_PEEKUSER.
>
>So, I wonder how much work it is to improve ptrace in compat_linux and
>compat_linux32?

Should not be that hard, but what is that tool reading from PEEKUSER?
Registers?

christos