linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jon Foster <jon@jon-foster.co.uk>
To: linux-kernel@vger.kernel.org
Cc: zwane@arm.linux.org.uk
Subject: Re:Re: [PATCH][2.6-mm] Fix 4G/4G X11/vm86 oops
Date: Tue, 18 Nov 2003 23:48:47 +0000	[thread overview]
Message-ID: <3FBAAFDF.5000803@jon-foster.co.uk> (raw)

Hi,

> The other thing I've found printks to hide before is timing bugs / races.
> Unfortunately I can't see one here, but maybe someone else can ;-)
> Maybe inserting a 1ms delay or something in place of the printk would
> have the same effect?

One of my colleagues had an interesting bug caused by an
uninitialized variable - a printk() in the right place happened
to set the variable (which gcc had put in a register) to the
correct value for his code to work.

I've tried looking for uses of uninitialized registers in entry.S,
but the assembly there isn't easy to follow.

What happens if you replace the printk with assembly code
that clobbers eax, ecx, edx and (most of) eflags?  (Assuming
I've remembered the calling convention correctly, those are
the registers that printk will be overwriting).

Kind regards,

Jon


             reply	other threads:[~2003-11-18 23:49 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-11-18 23:48 Jon Foster [this message]
2003-11-19  3:24 ` Re:Re: [PATCH][2.6-mm] Fix 4G/4G X11/vm86 oops Zwane Mwaikambo
2003-11-19  5:45   ` Andrew Morton
2003-11-19  6:50     ` Zwane Mwaikambo
2003-11-19  7:24       ` Linus Torvalds

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=3FBAAFDF.5000803@jon-foster.co.uk \
    --to=jon@jon-foster.co.uk \
    --cc=linux-kernel@vger.kernel.org \
    --cc=zwane@arm.linux.org.uk \
    /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).