From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58702) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SCFQZ-0006a0-Ap for qemu-devel@nongnu.org; Mon, 26 Mar 2012 15:18:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SCFQX-0005M2-71 for qemu-devel@nongnu.org; Mon, 26 Mar 2012 15:18:02 -0400 Received: from mail-ob0-f173.google.com ([209.85.214.173]:62085) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SCFQX-0005JJ-21 for qemu-devel@nongnu.org; Mon, 26 Mar 2012 15:18:01 -0400 Received: by obbwd20 with SMTP id wd20so6371634obb.4 for ; Mon, 26 Mar 2012 12:17:59 -0700 (PDT) Message-ID: <4F70C0E4.9000700@codemonkey.ws> Date: Mon, 26 Mar 2012 14:17:56 -0500 From: Anthony Liguori MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] fix multiboot loading if load_end_addr == 0 (fwd) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Scott Moser Cc: qemu-devel@nongnu.org On 03/18/2012 12:45 PM, Scott Moser wrote: > Re-sending to qemu-devel. I'd originally sent this to kvm mailing list. Can you submit as a proper patch with a Signed-off-by? Regards, Anthony Liguori > > ---------- Forwarded message ---------- > Date: Sat, 17 Mar 2012 00:08:06 > From: Scott Moser > To: kvm@vger.kernel.org > Subject: [PATCH] fix multiboot loading if load_end_addr == 0 > > The previous code did not treat the case where load_end_addr was 0 > specially. The multiboot specification says the following: > * load_end_addr > Contains the physical address of the end of the data segment. > (load_end_addr - load_addr) specifies how much data to load. This > implies that the text and data segments must be consecutive in the > OS image; this is true for existing a.out executable formats. If > this field is zero, the boot loader assumes that the text and data > segments occupy the whole OS image file. > > This was raised initially as launchpad bug > https://bugs.launchpad.net/qemu/+bug/957622 > > diff --git a/hw/multiboot.c b/hw/multiboot.c > index b4484a3..b1e04c5 100644 > --- a/hw/multiboot.c > +++ b/hw/multiboot.c > @@ -202,10 +202,16 @@ int load_multiboot(void *fw_cfg, > uint32_t mh_bss_end_addr = ldl_p(header+i+24); > mh_load_addr = ldl_p(header+i+16); > uint32_t mb_kernel_text_offset = i - (mh_header_addr - mh_load_addr); > - uint32_t mb_load_size = mh_load_end_addr - mh_load_addr; > - > + uint32_t mb_load_size = 0; > mh_entry_addr = ldl_p(header+i+28); > - mb_kernel_size = mh_bss_end_addr - mh_load_addr; > + > + if (mh_load_end_addr) { > + mb_kernel_size = mh_bss_end_addr - mh_load_addr; > + mb_load_size = mh_load_end_addr - mh_load_addr; > + } else { > + mb_kernel_size = kernel_file_size - mb_kernel_text_offset; > + mb_load_size = mb_kernel_size; > + } > > /* Valid if mh_flags sets MULTIBOOT_HEADER_HAS_VBE. > uint32_t mh_mode_type = ldl_p(header+i+32); > >