LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Ian Campbell <ijc@hellion.org.uk>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander van Heukelum <heukelum@mailshack.com>,
Ingo Molnar <mingo@elte.hu>,
Alexander van Heukelum <heukelum@fastmail.fm>,
Andi Kleen <ak@suse.de>, Thomas Gleixner <tglx@linutronix.de>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Mark McLoughlin <markmc@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] use realmode code to reserve end-of-conventional-memory to 1MB
Date: Thu, 28 Feb 2008 23:16:49 +0000 [thread overview]
Message-ID: <1204240609.28798.33.camel@cthulhu.hellion.org.uk> (raw)
In-Reply-To: <47C72432.3010606@zytor.com>
On Thu, 2008-02-28 at 13:14 -0800, H. Peter Anvin wrote:
> Ian Campbell wrote:
> > On Thu, 2008-02-28 at 14:28 +0100, Alexander van Heukelum wrote:
> >> Instead of using early reservations inside the kernel code,
> >> we could use the realmode code to modify the e820 memmap.
> >> This patch shows what that would look like. I have not looked
> >> at the case where the BIOS does not provide an e820 memmap
> >> yet. Probably a full solution would need to create a fake
> >> e820 memmap in that case.
> >
> > An e820 is already faked up in machine_specific_memory_setup() if one
> > doesn't already exist.
> >
> >> Comments?
> >
> > This won't work for Xen since the real-mode code never runs there. I
> > think it could be fixed in xen_memory_setup() though if native goes down
> > this route.
> >
>
> s/could/should/.
>
> You need to set up your memory map more sensibly; it's not just the
> kernel, user space tries to access these areas too.
Agreed, I think it's pure luck that Xen kernels have gotten away with it
in the past.
The patch below seems like the right thing to do. It certainly boots in
a domU without the DMI problem (without any of the other related patches
such as Alexander's).
However ddcprobe hangs when run -- need to investigate some more, vm86
in general works ok (i.e. my vm86 test code passes).
BTW Jeremy, the kernel doesn't use XENMEM_memory_map -- any reason other
than it not being useful at the time? These days the tools can push an
arbitrary e820 down for a guest which might be useful to support,
although nothing interesting is done with it today.
Ian.
x86/xen: Construct e820 map with a hole between 640K-1M.
Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
---
arch/x86/xen/setup.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 3bad477..2341492 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -38,7 +38,8 @@ char * __init xen_memory_setup(void)
unsigned long max_pfn = xen_start_info->nr_pages;
e820.nr_map = 0;
- add_memory_region(0, PFN_PHYS(max_pfn), E820_RAM);
+ add_memory_region(0, LOWMEMSIZE(), E820_RAM);
+ add_memory_region(HIGH_MEMORY, PFN_PHYS(max_pfn)-HIGH_MEMORY, E820_RAM);
return "Xen";
}
--
1.5.4.2
--
Ian Campbell
His mind is like a steel trap: full of mice.
-- Foghorn Leghorn
next prev parent reply other threads:[~2008-02-28 23:17 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-24 17:46 [PATCH] Fix alignment of early reservation for EBDA Alexander van Heukelum
2008-02-24 19:27 ` Andi Kleen
2008-02-24 19:41 ` Ingo Molnar
2008-02-24 20:53 ` Alexander van Heukelum
2008-02-25 2:18 ` H. Peter Anvin
2008-02-25 16:54 ` Alexander van Heukelum
2008-02-25 17:01 ` Ingo Molnar
2008-02-25 18:07 ` [PATCH] reserve_early end-of-conventional-memory to 1MB Alexander van Heukelum
2008-02-25 18:13 ` H. Peter Anvin
2008-02-25 19:46 ` Alexander van Heukelum
2008-02-25 21:17 ` H. Peter Anvin
2008-02-26 9:30 ` Ingo Molnar
2008-02-27 14:26 ` Andi Kleen
2008-02-27 14:38 ` [PATCH] reserve_early end-of-conventional-memory to 1MB II - some numbers to put it into perspective Andi Kleen
2008-02-27 16:44 ` H. Peter Anvin
2008-02-27 20:01 ` Alexander van Heukelum
2008-02-28 13:13 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit Alexander van Heukelum
2008-02-28 13:28 ` [RFC] use realmode code to reserve end-of-conventional-memory to 1MB Alexander van Heukelum
2008-02-28 21:12 ` Ian Campbell
2008-02-28 21:14 ` H. Peter Anvin
2008-02-28 23:16 ` Ian Campbell [this message]
2008-02-29 20:00 ` Ingo Molnar
2008-03-04 11:41 ` Mark McLoughlin
2008-03-04 14:33 ` Ingo Molnar
2008-03-04 15:12 ` Ian Campbell
2008-03-04 15:13 ` Jeremy Fitzhardinge
2008-03-04 15:25 ` Ingo Molnar
2008-03-04 16:02 ` Jeremy Fitzhardinge
2008-03-04 16:15 ` Ingo Molnar
2008-03-04 16:15 ` Mark McLoughlin
2008-03-04 16:23 ` Ingo Molnar
2008-03-04 17:44 ` Jeremy Fitzhardinge
2008-03-05 15:59 ` Eduardo Habkost
2008-03-05 16:08 ` H. Peter Anvin
2008-03-05 16:53 ` Eduardo Habkost
2008-03-05 17:28 ` H. Peter Anvin
2008-03-05 17:28 ` Jeremy Fitzhardinge
2008-03-05 17:38 ` H. Peter Anvin
2008-03-05 16:38 ` Jeremy Fitzhardinge
2008-03-05 17:27 ` H. Peter Anvin
2008-02-28 21:09 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit Ian Campbell
2008-02-29 11:49 ` Alexander van Heukelum
2008-02-29 17:14 ` Mark McLoughlin
2008-02-29 18:38 ` Alexander van Heukelum
2008-02-29 18:44 ` H. Peter Anvin
2008-02-29 18:56 ` Alexander van Heukelum
2008-02-29 22:06 ` Mark McLoughlin
2008-02-29 22:26 ` Alexander van Heukelum
2008-03-01 16:09 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit v2 Alexander van Heukelum
2008-03-01 16:12 ` [PATCH] reserve end-of-conventional-memory to 1MB on 64-bit add-on Alexander van Heukelum
2008-03-04 11:44 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit v2 Mark McLoughlin
2008-03-04 13:31 ` Alexander van Heukelum
2008-03-04 14:49 ` Ingo Molnar
2008-03-04 15:16 ` Mark McLoughlin
2008-03-04 15:24 ` Ingo Molnar
2008-03-04 15:18 ` Jeremy Fitzhardinge
2008-03-04 16:51 ` Alexander van Heukelum
2008-03-04 17:05 ` H. Peter Anvin
2008-03-04 17:11 ` Jeremy Fitzhardinge
2008-03-04 18:57 ` [PATCH] reserve end-of-conventional-memory to 1MB, 32-bit, use paravirt_enabled Alexander van Heukelum
2008-03-04 19:12 ` [PATCH] reserve end-of-conventional-memory to 1MB, 64-bit, " Alexander van Heukelum
2008-02-27 14:25 ` [PATCH] Fix alignment of early reservation for EBDA Andi Kleen
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=1204240609.28798.33.camel@cthulhu.hellion.org.uk \
--to=ijc@hellion.org.uk \
--cc=ak@suse.de \
--cc=heukelum@fastmail.fm \
--cc=heukelum@mailshack.com \
--cc=hpa@zytor.com \
--cc=jeremy@goop.org \
--cc=linux-kernel@vger.kernel.org \
--cc=markmc@redhat.com \
--cc=mingo@elte.hu \
--cc=tglx@linutronix.de \
--subject='Re: [RFC] use realmode code to reserve end-of-conventional-memory to 1MB' \
/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
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).