From: "Michael S. Tsirkin" <mst@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin OConnor <kevin@koconnor.net>, John Snow <jsnow@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Qemu-devel] Recent SeaBIOS too big for QEMU -initrd
Date: Wed, 20 Aug 2014 13:27:25 +0200 [thread overview]
Message-ID: <20140820112725.GF17371@redhat.com> (raw)
In-Reply-To: <CAJSP0QW570KVTSg5wgML0_9Y9pfORCFLL4757OUzvq572q6zHQ@mail.gmail.com>
On Wed, Aug 20, 2014 at 11:27:41AM +0100, Stefan Hajnoczi wrote:
> The QEMU -initrd option loads the initrd at the top of RAM. There is
> a 64 KB safety region for ACPI tables in hw/i386/pc.c:load_linux():
>
> initrd_max = max_ram_size-ACPI_DATA_SIZE-1;
>
> QEMU's bios-256k.bin SeaBIOS build reserves 128 KB at the top of
> memory so the 64 KB ACPI data size has become too small.
>
> The guest Linux kernel rejects the initrd:
> BIOS-provided physical RAM map:
> BIOS-e820: 0000000000010000 - 000000000009fc00 (usable)
> BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
> BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
> BIOS-e820: 0000000000100000 - 000000003ffe0000 (usable)
> BIOS-e820: 000000003ffe0000 - 0000000040000000 (reserved)
> BIOS-e820: 00000000feffc000 - 00000000ff000000 (reserved)
> BIOS-e820: 00000000fffc0000 - 0000000100000000 (reserved)
> ...
> initrd extends beyond end of memory (0x3ffef79f > 0x3ffe0000)
> disabling initrd
>
> It is easy enough to "fix" the problem by bumping ACPI_DATA_SIZE up to
> 0x20000 in QEMU. Perhaps this should only be done for bios-256k.bin
> guests and not bios-128k.bin guests (QEMU 1.7 and older machine
> types).
>
> Perhaps QEMU -> SeaBIOS -> linuxboot.bin can be simplified so QEMU
> doesn't have to guess what e820 region SeaBIOS will reserve.
> linuxboot.bin would probably be the place to do it unless SeaBIOS has
> Linux loading functionality that could be reused.
>
> Any ideas?
>
> Stefan
I would say 2.1 and up, -M pc-i440fx-2.0 works fine, or am I mistaken?
next prev parent reply other threads:[~2014-08-20 11:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-20 10:27 [Qemu-devel] Recent SeaBIOS too big for QEMU -initrd Stefan Hajnoczi
2014-08-20 11:27 ` Michael S. Tsirkin [this message]
2014-08-20 12:58 ` Stefan Hajnoczi
2014-08-20 20:58 ` Michael S. Tsirkin
2014-08-20 22:17 ` Kevin O'Connor
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