From: Chris Malley <mail@chrismalley.co.uk>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jeremy Fitzhardinge <jeremy@goop.org>, lguest <lguest@ozlabs.org>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
Vivek Goyal <vgoyal@in.ibm.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 5/5] lguest: loading bzImage directly
Date: Wed, 03 Oct 2007 10:37:01 +0100 [thread overview]
Message-ID: <1191404221.17247.15.camel@feisty> (raw)
In-Reply-To: <1191368457.17826.53.camel@localhost.localdomain>
Hi guys
Would it not be clearer to #include <asm/bootparam.h> and use
the relevant named members of struct setup_header / struct boot_params
rather than the hard-coded values 0x202, 0x1F1, 0x214 ?
--
Chris
On Wed, 2007-10-03 at 09:40 +1000, Rusty Russell wrote:
[snip]
> + u8 hdr[1024];
> + int r;
> + /* Modern bzImages get loaded at 1M. */
> + void *p = from_guest_phys(0x100000);
> +
> + /* Go back to the start of the file and read the header. It should be
> + * a Linux boot header (see Documentation/i386/boot.txt) */
> + lseek(fd, 0, SEEK_SET);
> + read(fd, hdr, sizeof(hdr));
> +
> + /* At offset 0x202, we expect the magic "HdrS" */
> + if (memcmp(hdr + 0x202, "HdrS", 4) != 0)
> + errx(1, "This doesn't look like a bzImage to me");
> +
> + /* The byte at 0x1F1 tells us how many extra sectors of
> + * header: skip over them all. */
> + lseek(fd, (unsigned long)(hdr[0x1F1]+1) * 512, SEEK_SET);
> +
> + /* Now read everything into memory. in nice big chunks. */
> + while ((r = read(fd, p, 65536)) > 0)
> + p += r;
> +
> + /* Finally, 0x214 tells us where to start the kernel. */
> + return *(unsigned long *)&hdr[0x214];
> }
>
> /*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels
>
next prev parent reply other threads:[~2007-10-03 9:44 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 [this message]
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
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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