From: Michael Ellerman <mpe@ellerman•id.au>
To: dwalker@fifo99•com
Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: simple_alloc space tramples initrd
Date: Tue, 12 Jan 2016 09:17:53 +1100 [thread overview]
Message-ID: <1452550673.23317.1.camel@ellerman.id.au> (raw)
In-Reply-To: <20160111164916.GA18065@fifo99.com>
On Mon, 2016-01-11 at 08:49 -0800, dwalker@fifo99•com wrote:
> On Mon, Jan 11, 2016 at 02:09:34PM +1100, Michael Ellerman wrote:
> > On Fri, 2016-01-08 at 09:45 -0800, dwalker@fifo99•com wrote:
> > > Hi,
> > >
> > > A powerpc machine I'm working on has this problem where the
> > > simple_alloc_init() area is trampling the initrd. The two are placed fairly
> > > close together.
> >
> > Which machine / platform?
>
> It's not upstream yet. I'm still putting the patches together, that's when this
> issue came up. I can send an RFC if you want to look at the patches.
OK. Thanks but I don't need more patches to look at :)
I was just trying to narrow down which code you were talking about.
> > I don't really know that code very well. But ideally either the boot loader
> > gives you space, or the platform boot code is smart enough to detect that there
> > is insufficient room and puts the heap somewhere else.
>
> It seems like the kernel should be able to handle it. I believe the bootloader passes
> the initrd location , but I don't think it's evaluated till later in the boot up. For
> simple_alloc_init() it seems all platforms just assume the space is empty without checking.
Yeah that's what I see too, which seems like it's liable to break, but
obviously hasn't for anyone else yet.
The bootloader must pass the initrd location, otherwise the kernel can't use
it, so it seems like the kernel should be able to notice when they are too
close. But it may be complicated by the sequencing of the code.
cheers
next prev parent reply other threads:[~2016-01-11 22:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-08 17:45 simple_alloc space tramples initrd dwalker
2016-01-11 3:09 ` Michael Ellerman
2016-01-11 16:49 ` dwalker
2016-01-11 22:17 ` Michael Ellerman [this message]
2016-01-11 23:07 ` dwalker
2016-01-11 23:37 ` Michael Ellerman
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=1452550673.23317.1.camel@ellerman.id.au \
--to=mpe@ellerman$(echo .)id.au \
--cc=benh@kernel$(echo .)crashing.org \
--cc=dwalker@fifo99$(echo .)com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=paulus@samba$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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