[Qemu-devel] /dev/mtd emulation

[Qemu-devel] /dev/mtd emulation

[Anton L. Vinokurov]

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Dear Developers,

I am struggling to run some exotic box firmware inside of QEMU. Originally it is i386 processor, MontaVista-Linux based appliance. I was able to boot and run it, but main guest application fails while reading from /dev/mtd1 (generic open()). To my understanding, it is a some form of onboard flash, which I don't have inside of QEMU guest:

~ # uname -a
Linux (none) 2.6.10_mvl401 #1 Tue Jun 1 15:50:57 PDT 2010 i686 unknown
~ # ls -la /dev/mtd*
crw-r--r--    1 root     root      90,   0 Oct 16  2008 /dev/mtd0
crw-r--r--    1 root     root      90,   2 Oct 16  2008 /dev/mtd1
crw-r--r--    1 root     root      90,   4 Oct 16  2008 /dev/mtd2
...
~ # cat /proc/mtd
dev:    size   erasesize  name
~ # dmesg | grep mtd
~ #

Well, I am fine to write some emulation code, ideally to map some host file to make It visible as /dev/mtdX from the guest. Would you please give me some hint where to start from?
Unfortunately, neither 2.6.10_mvl401 sources nor physical appliance itself are not available to me.

Regards,

Anton Vinokurov
anton@netams.com<mailto:anton@netams.com>




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Re: [Qemu-devel] /dev/mtd emulation

[Stefan Hajnoczi]

On Wed, Feb 9, 2011 at 7:18 AM, Anton L. Vinokurov <anton@netams.com> wrote:
> ~ # dmesg | grep mtd
>
> ~ #

Have you tried qemu -drive if=mtd,file=/path/to/firmware?

QEMU has some flash emulation code in
hw/{nand.c,onenand.c,pflash_cfi01.c,pflash_cfi02.c}.  I've never used
them but perhaps someone else can help if you provide more details
about the hardware you are trying to emulate.

Stefan

[Qemu-devel] Re: /dev/mtd emulation

[Jan Kiszka]

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On 2011-02-09 09:13, Stefan Hajnoczi wrote:
> On Wed, Feb 9, 2011 at 7:18 AM, Anton L. Vinokurov <anton@netams.com> wrote:
>> ~ # dmesg | grep mtd
>>
>> ~ #
> 
> Have you tried qemu -drive if=mtd,file=/path/to/firmware?
> 
> QEMU has some flash emulation code in
> hw/{nand.c,onenand.c,pflash_cfi01.c,pflash_cfi02.c}.  I've never used
> them but perhaps someone else can help if you provide more details
> about the hardware you are trying to emulate.

You also need to wire up that flash device on board init, i.e. add some
pflash_*_register to pc_init1. Check some embedded board for the precise
pattern.

Jan


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[Qemu-devel] RE: /dev/mtd emulation

[Anton L. Vinokurov]

Jan, Stefan,

I've tried indeed but with no luck:
(qemu) info block
ide0-hd0: type=hd removable=0 file=vimage.dat ro=0 drv=raw encrypted=0
mtd0: type=hd removable=0 file=firmware.bin ro=0 drv=raw encrypted=0
floppy0: type=floppy removable=1 locked=0 [not inserted]
sd0: type=floppy removable=1 locked=0 [not inserted]

but same time:
~ # cat /dev/mtd0
cat: /dev/mtd0: No such device
~ # cat /dev/mtdblock0
cat: /dev/mtdblock0: No such device or address

Guest /dev/mtd0 is character device but QEMU thinks mtd0 is block.

My hardware is a network module (like NME-CUE, NME-APPRE, NME-WAE) for Cisco ISR routers: 1GHz Celeron CPU, CompactFlash disk, 1Gb DRAM, 1 FastEthernet, ... Flash memory chip is STM M50FW080 8Mbit NVRAM.

Regards,

Anton.


-----Original Message-----
From: jan.kiszka@web.de [mailto:jan.kiszka@web.de] 
Sent: Wednesday, February 09, 2011 11:47 AM
To: Stefan Hajnoczi
Cc: Anton L. Vinokurov; qemu-devel@nongnu.org
Subject: Re: /dev/mtd emulation

On 2011-02-09 09:13, Stefan Hajnoczi wrote:
> On Wed, Feb 9, 2011 at 7:18 AM, Anton L. Vinokurov <anton@netams.com> wrote:
>> ~ # dmesg | grep mtd
>>
>> ~ #
> 
> Have you tried qemu -drive if=mtd,file=/path/to/firmware?
> 
> QEMU has some flash emulation code in
> hw/{nand.c,onenand.c,pflash_cfi01.c,pflash_cfi02.c}.  I've never used
> them but perhaps someone else can help if you provide more details
> about the hardware you are trying to emulate.

You also need to wire up that flash device on board init, i.e. add some
pflash_*_register to pc_init1. Check some embedded board for the precise
pattern.

Jan

Re: [Qemu-devel] RE: /dev/mtd emulation

[Artyom Tarasenko]

On Wed, Feb 9, 2011 at 4:34 PM, Anton L. Vinokurov <anton@netams.com> wrote:
> Jan, Stefan,
>
> I've tried indeed but with no luck:
> (qemu) info block
> ide0-hd0: type=hd removable=0 file=vimage.dat ro=0 drv=raw encrypted=0
> mtd0: type=hd removable=0 file=firmware.bin ro=0 drv=raw encrypted=0
> floppy0: type=floppy removable=1 locked=0 [not inserted]
> sd0: type=floppy removable=1 locked=0 [not inserted]
>
> but same time:
> ~ # cat /dev/mtd0
> cat: /dev/mtd0: No such device
> ~ # cat /dev/mtdblock0
> cat: /dev/mtdblock0: No such device or address


Looks like your guest kernel expects some other type of flash, or
looks for it not where you wired it up?
Maybe there are some hints in the dmesg output?

> Guest /dev/mtd0 is character device but QEMU thinks mtd0 is block.
>
> My hardware is a network module (like NME-CUE, NME-APPRE, NME-WAE) for Cisco ISR routers: 1GHz Celeron CPU, CompactFlash disk, 1Gb DRAM, 1 FastEthernet, ... Flash memory chip is STM M50FW080 8Mbit NVRAM.
>
> Regards,
>
> Anton.
>
>
> -----Original Message-----
> From: jan.kiszka@web.de [mailto:jan.kiszka@web.de]
> Sent: Wednesday, February 09, 2011 11:47 AM
> To: Stefan Hajnoczi
> Cc: Anton L. Vinokurov; qemu-devel@nongnu.org
> Subject: Re: /dev/mtd emulation
>
> On 2011-02-09 09:13, Stefan Hajnoczi wrote:
>> On Wed, Feb 9, 2011 at 7:18 AM, Anton L. Vinokurov <anton@netams.com> wrote:
>>> ~ # dmesg | grep mtd
>>>
>>> ~ #
>>
>> Have you tried qemu -drive if=mtd,file=/path/to/firmware?
>>
>> QEMU has some flash emulation code in
>> hw/{nand.c,onenand.c,pflash_cfi01.c,pflash_cfi02.c}.  I've never used
>> them but perhaps someone else can help if you provide more details
>> about the hardware you are trying to emulate.
>
> You also need to wire up that flash device on board init, i.e. add some
> pflash_*_register to pc_init1. Check some embedded board for the precise
> pattern.
>
> Jan
>
>
>



-- 
Regards,
Artyom Tarasenko

solaris/sparc under qemu blog: http://tyom.blogspot.com/