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Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one fl
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive |
Date: |
Wed, 27 Nov 2013 15:45:11 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
Laszlo Ersek <address@hidden> writes:
> On 11/27/13 14:52, Markus Armbruster wrote:
>> Jordan Justen <address@hidden> writes:
>>
>>> On Tue, Nov 26, 2013 at 5:32 AM, Laszlo Ersek <address@hidden> wrote:
>>>> On 11/26/13 13:36, Markus Armbruster wrote:
>>>>
>>>>> Your stated purpose for multiple -pflash:
>>>>>
>>>>> This accommodates the following use case: suppose that OVMF is split
>>>>> in
>>>>> two parts, a writeable host file for non-volatile variable
>>>>> storage, and a
>>>>> read-only part for bootstrap and decompressible executable code.
>>>>>
>>>>> Such a split between writable part and read-only part makes sense to me.
>>>>> How is it done in physical hardware? Single device with configurable
>>>>> write-protect, or two separate devices?
>>>>
>>>> (Jordan could help more.)
>>>>
>>>> Likely one device that's fully writeable.
>>>
>>> Most parts will have a dedicated read-only line.
>>>
>>> Many devices have 'block-locking' that will make some subset of blocks
>>> read-only until a reset.
>>>
>>> In addition to this, many chipsets will allow flash writes to be
>>> protected by triggering SMM when a flash write occurs.
>>>
>>> Using multiple chips are less common due to cost, but this is not a
>>> factor for QEMU. :)
>>
>> Should we stick to what real hardware does? Single device, perhaps with
>> block locking.
>
> I can't back a single flash device with two drives (= two host-side
> files), which is the incentive for this change.
There's no fundamental reason why a single device model instance could
not be backed by two block backends, named by two drive properties.
I'm not claiming this is the best solution, just offering it for
consideration.
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, (continued)
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/22
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/22
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/25
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/25
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/26
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/26
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Jordan Justen, 2013/11/26
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/27
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/27
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive,
Markus Armbruster <=
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/27
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/27
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/27
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/27
- Re: [Qemu-devel] [edk2] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Paolo Bonzini, 2013/11/26
- Re: [Qemu-devel] [edk2] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/26
- Re: [Qemu-devel] [edk2] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Paolo Bonzini, 2013/11/26
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/26
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Laszlo Ersek, 2013/11/26
- Re: [Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive, Markus Armbruster, 2013/11/27