Re: [Qemu-devel] [QEMU] [PATCH v5 0/8] Add Qemu to SeaBIOS LCHS interface

From: Sam Eiderman <shmuel.eiderman@oracle.com>
To: Kevin Wolf <kwolf@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>,
	Laszlo Ersek <lersek@redhat.com>,
	philmd@redhat.com
Cc: qemu-block@nongnu.org, Arbel Moshe <arbel.moshe@oracle.com>,
	seabios@seabios.org, QEMU <qemu-devel@nongnu.org>,
	Max Reitz <mreitz@redhat.com>,
	Kevin O'Connor <kevin@koconnor.net>,
	Liran Alon <liran.alon@oracle.com>,
	Karl Heubaum <karl.heubaum@oracle.com>
Subject: Re: [Qemu-devel] [QEMU] [PATCH v5 0/8] Add Qemu to SeaBIOS LCHS interface
Date: Fri, 19 Jul 2019 13:10:04 +0300	[thread overview]
Message-ID: <65B72D23-26BE-4C3B-B298-A6231D08BF6C@oracle.com> (raw)
In-Reply-To: <20190717194623.GF6471@localhost.localdomain>

Well, this patch introduces 3 command line parameters (“lcyls”, “lheads”, “lsecs”)
to “scsi-hd” “ide-hd” and “virtio-pci-blk” so this somehow has something to do with
block.

This patch also adds fw_cfg interface to send these parameters to SeaBIOS.

"scripts/get_maintainer.pl -f hw/nvram/fw_cfg.c” gives

"Philippe Mathieu-Daudé" <philmd@redhat.com> (supporter:Firmware configur...)
Laszlo Ersek <lersek@redhat.com> (reviewer:Firmware configur...)
Gerd Hoffmann <kraxel@redhat.com> (reviewer:Firmware configur…)

And this was already Reviewed-by Gerd.

How should I proceed?

Sam

> On 17 Jul 2019, at 22:46, Kevin Wolf <kwolf@redhat.com> wrote:
> 
> Am 17.07.2019 um 21:03 hat Sam Eiderman geschrieben:
>> Gentle ping.
> 
> Through which tree is this supposed to go? I feel this is more firmware
> interface related than block layer stuff.
> 
> Kevin
> 
>>> On 8 Jul 2019, at 20:30, Sam Eiderman <shmuel.eiderman@oracle.com> wrote:
>>> 
>>> Thanks Gerd,
>>> 
>>> Gentle ping on this.
>>> 
>>> Sam
>>> 
>>>> On 1 Jul 2019, at 10:41, Gerd Hoffmann <kraxel@redhat.com> wrote:
>>>> 
>>>> On Wed, Jun 26, 2019 at 03:39:40PM +0300, Sam Eiderman wrote:
>>>>> v1:
>>>>> 
>>>>> Non-standard logical geometries break under QEMU.
>>>>> 
>>>>> A virtual disk which contains an operating system which depends on
>>>>> logical geometries (consistent values being reported from BIOS INT13
>>>>> AH=08) will most likely break under QEMU/SeaBIOS if it has non-standard
>>>>> logical geometries - for example 56 SPT (sectors per track).
>>>>> No matter what QEMU will guess - SeaBIOS, for large enough disks - will
>>>>> use LBA translation, which will report 63 SPT instead.
>>>>> 
>>>>> In addition we can not enforce SeaBIOS to rely on phyiscal geometries at
>>>>> all. A virtio-blk-pci virtual disk with 255 phyiscal heads can not
>>>>> report more than 16 physical heads when moved to an IDE controller, the
>>>>> ATA spec allows a maximum of 16 heads - this is an artifact of
>>>>> virtualization.
>>>>> 
>>>>> By supplying the logical geometies directly we are able to support such
>>>>> "exotic" disks.
>>>>> 
>>>>> We will use fw_cfg to do just that.
>>>>> 
>>>>> v2:
>>>>> 
>>>>> Fix missing parenthesis check in
>>>>>  "hd-geo-test: Add tests for lchs override"
>>>>> 
>>>>> v3:
>>>>> 
>>>>> * Rename fw_cfg key to "bios-geometry".
>>>>> * Remove "extendible" interface.
>>>>> * Add cpu_to_le32 fix as Laszlo suggested or big endian hosts
>>>>> * Fix last qtest commit - automatic docker tester for some reason does not have qemu-img set
>>>>> 
>>>>> v4:
>>>>> 
>>>>> * Change fw_cfg interface from mixed textual/binary to textual only
>>>>> 
>>>>> v5:
>>>>> 
>>>>> * Fix line > 80 chars in tests/hd-geo-test.c
>>>> 
>>>> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
>>>> 
>>>> cheers,
>>>> Gerd
>>>> 
>>> 
>> 