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Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD |
Date: |
Sun, 17 Mar 2013 18:54:47 +0000 |
On 17 March 2013 18:51, Paolo Bonzini <address@hidden> wrote:
> Il 17/03/2013 01:04, Aurelien Jarno ha scritto:
>> | boot | install build-dep | build lm-sensors |
>> ------------------------+------+-------------------+------------------+
>> versatile | 1:09 | 2:27 | 4:09 |
>> versatile cache=wb | 1:08 | 2:25 | 3:44 |
>
> Strange, cache=wb should be the default.
>
> The real problem with SD is that it doesn't have a flush command, hence
> it cannot be made safe against power losses.
So, two things here:
(a) the way to make it safe against power loss is that when the
guest writes a block of data it has to really hit the emulated
disk, because this is how the hardware works
(b) I thought this was the reason cache=wb wasn't the default (ie
that we weren't defaulting to 'may lose data on powerloss'). At the
time I last looked into command line options for these boards I'm
pretty sure it wasn't the default, because the performance improvement
from turning on caching was huge.
-- PMM
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, (continued)
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Aurelien Jarno, 2013/03/04
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Markus Armbruster, 2013/03/06
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Peter Maydell, 2013/03/15
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Aurelien Jarno, 2013/03/15
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Peter Maydell, 2013/03/15
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Aurelien Jarno, 2013/03/16
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Peter Maydell, 2013/03/16
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Aurelien Jarno, 2013/03/17
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Peter Maydell, 2013/03/17
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Paolo Bonzini, 2013/03/17
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Aurelien Jarno, 2013/03/17
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Paolo Bonzini, 2013/03/18
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Aurelien Jarno, 2013/03/17
- Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD, Paolo Bonzini, 2013/03/17