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Date: Thu, 30 Jan 2014 15:39:25 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20140130143925.GC15494@stefanha-thinkpad.redhat.com>
References: <1391087282-17686-1-git-send-email-pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block: handle "rechs" translation option
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com

On Thu, Jan 30, 2014 at 02:08:02PM +0100, Paolo Bonzini wrote:
> The rechs translation option is so obscure that we support it but do
> not even attempt to parse it.  Archeologists will surely be puzzled
> by this (assuming they care about QEMU and CHS translation), so fix it.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  blockdev.c |  2 ++
>  vl.c       | 18 ++++++++++++------
>  2 files changed, 14 insertions(+), 6 deletions(-)

Is my understanding correct that QEMU actually does nothing with RECHS except
poke a magic number into CMOS memory when x86 guests start?

(I ask because we don't even use the constant:
$ git grep _RECHS
include/hw/block/block.h:#define BIOS_ATA_TRANSLATION_RECHS  4)

Please also add changes for:

blockdev.c:
QemuOptsList qemu_legacy_drive_opts = {
        ...
        },{
            .name = "trans",
            .type = QEMU_OPT_STRING,
            .help = "chs translation (auto, lba, none)",
        },{

qemu-options.hx:
Force hard disk 0 physical geometry (1 <= @var{c} <= 16383, 1 <=
@var{h} <= 16, 1 <= @var{s} <= 63) and optionally force the BIOS
translation mode (@var{t}=none, lba or auto).