From: John Reiser <jreiser@BitWagon.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] bug: qemu-0.9.0 emulating mipsel (32-bit R3000) on amd64
Date: Tue, 08 May 2007 16:50:07 -0700 [thread overview]
Message-ID: <46410CAF.50809@BitWagon.com> (raw)
In-Reply-To: <20070506200452.GA32686@networkno.de>
>>qemu-0.9.0 ...
>>emulating Debian 2.6.18-4-qemu mipsel ...
>>errs when gdb 6.4.90-debian (running on the emulated mipsel)
>>single-steps the user-mode instruction ...
> This looks like another instance of "Qemu/MIPS doesn't handle
> self-modifying code correctly" (the break instructions inserted
> by gdb are exactly this).
No, the usage by gdb does *not* qualify as "self-modifying code."
gdb uses the system call ptrace(PTRACE_POKETEXT, pid, addr, data)
to have the emulated operating system kernel itself modify the memory
of the child process. Nobody has to guess or to "snoop" the memory
bus in order to discover that the instruction stream is being modified.
Instead, there is direct notification of what is happening. If nothing
else, then under CONFIG_QEMU the implementation of sys_ptrace()
must notify the emulator to flush the appropriate translations.
--
John Reiser, jreiser@BitWagon.com
next prev parent reply other threads:[~2007-05-08 23:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-06 18:45 [Qemu-devel] bug: qemu-0.9.0 emulating mipsel (32-bit R3000) on amd64 John Reiser
2007-05-06 20:04 ` Thiemo Seufer
2007-05-06 20:07 ` Thiemo Seufer
2007-05-07 12:13 ` Daniel Jacobowitz
2007-05-07 15:46 ` Paul Brook
2007-05-07 22:46 ` [Qemu-devel] workaround: " John Reiser
2007-05-07 23:03 ` Paul Brook
2007-05-07 23:08 ` Paul Brook
2007-05-08 18:03 ` [Qemu-devel] bug: " Stefan Weil
2007-05-08 23:50 ` John Reiser [this message]
2007-05-09 1:04 ` Thiemo Seufer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=46410CAF.50809@BitWagon.com \
--to=jreiser@bitwagon.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).