From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Vivek Goyal <vgoyal@in.ibm.com>, lguest <lguest@ozlabs.org>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH 0/5] Boot protocol changes
Date: Tue, 02 Oct 2007 17:43:44 -0700 [thread overview]
Message-ID: <4702E5C0.5040606@zytor.com> (raw)
In-Reply-To: <4702DAB5.6090003@goop.org>
Jeremy Fitzhardinge wrote:
> H. Peter Anvin wrote:
>>> This series looks like a good start for Xen, but we still need to work
>>> out where to stash the metadata which normally lives in ELF notes.
>>> Using ELF is convenient for Xen because it lets a large chunk of domain
>>> builder code be reused; on the other hand, loading a plain bzImage is
>>> pretty simple, so maybe it isn't such a big deal.
>>>
>>> HPA, Eric: if we don't go the "embed ELF" path, where's a good
>>> backwards-compatible place to stash the note data? If we do go with
>>> "embed ELF", how should we go about doing it? Arrange to put the ELF
>>> headers before the 1M mark?
>>>
>> This sounds like another good reason to do the ELF image as the
>> postcompression image. The interface to the embedded compression
>> routine is then unchanged, and we get the "full vmlinux" with any
>> notes that belongs there.
>>
>> I'll try to get an implementation of that done -- it really shouldn't
>> be very hard.
>
> Please explain what you're proposing again, because my memory of your
> plan from last time wouldn't help in this case. Are you proposing that
> the bzImage contains compressed data that its expecting the bootloader
> to decompress? Won't that completely break backwards compatibility? If
> we don't care about backwards compatibility with old bootloaders, then
> it doesn't matter what we do one way or the other.
>
No, not at all.
I'm proposing that the existing bzImage format be retained, but that the
payload of the decompressor (already a gzip file) simply be vmlinux.gz
-- i.e. a gzip compressed ELF file, notes and all. A pointer in the
header will point to the offset of the payload (this is new, obviously.)
The decompression stub is adjusted to expect an ELF image, instead of a
raw binary.
Existing bootloaders (16- or 32-bit) simply load the bzImage the way
they do now; new bootloaders have the option of accessing the vmlinux.gz
directly if they either want to load it themselves or want to examine
the notes.
-hpa
next prev parent reply other threads:[~2007-10-03 0:44 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-02 23:34 [PATCH 0/5] Boot protocol changes Rusty Russell
2007-10-02 23:35 ` [PATCH 1/5] update boot spec to 2.07 Rusty Russell
2007-10-02 23:35 ` [PATCH 2/5] add WEAK() for creating weak asm labels Rusty Russell
2007-10-02 23:36 ` [PATCH 3/5] i386: paravirt boot sequence Rusty Russell
2007-10-02 23:39 ` [PATCH 4/5] Revert lguest magic and use hook in head.S Rusty Russell
2007-10-02 23:40 ` [PATCH 5/5] lguest: loading bzImage directly Rusty Russell
2007-10-03 9:37 ` Chris Malley
2007-10-03 17:12 ` H. Peter Anvin
2007-10-04 0:02 ` Rusty Russell
2007-10-04 0:26 ` H. Peter Anvin
2007-11-24 21:54 ` Kjartan Maraas
2007-11-24 22:14 ` H. Peter Anvin
2007-11-25 12:32 ` Kjartan Maraas
2007-10-30 6:38 ` [PATCH 1/5] update boot spec to 2.07 rae l
2007-10-02 23:44 ` [PATCH 0/5] Boot protocol changes H. Peter Anvin
2007-10-02 23:46 ` Jeremy Fitzhardinge
2007-10-02 23:53 ` H. Peter Anvin
2007-10-02 23:56 ` Jeremy Fitzhardinge
2007-10-03 0:43 ` H. Peter Anvin [this message]
2007-10-03 0:46 ` H. Peter Anvin
2007-10-03 0:58 ` Jeremy Fitzhardinge
2007-10-03 1:03 ` H. Peter Anvin
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