klibc - Feb 2010 - why mtd root device number is __makedev(0,254)

Hi,
I'm wondering when /proc/cmdline has "root=/dev/mtdblockX",
name_to_dev_t_real will return __makedev(0,254) for root device's device
number
which is weired. I think we need to create the device on the fly from
information in sysfs.

Maybe I have mistaken something. Is there any clue?

-- 
Regards, Shizheng
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Hi,
I'm wondering when /proc/cmdline has "root=/dev/mtdblockX",
name_to_dev_t_real will return __makedev(0,254) for root device's device
number
which is weired. I think we need to create the device on the fly from
information in sysfs.

Maybe I have mistaken something. Is there any clue?

-- 
Regards, Shizheng
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hello,

On Thu, 25 Feb 2010, zheng shi wrote:
> Hi,
> I'm wondering when /proc/cmdline has "root=/dev/mtdblockX",
> name_to_dev_t_real will return __makedev(0,254) for root device's
device
> number
> which is weired. I think we need to create the device on the fly from
> information in sysfs.
> 
> Maybe I have mistaken something. Is there any clue?
what are you trying todo?
please more details and more specific.

aboves does look strange unless you have some special udev rules,
don't think device mtdblockX gets created in /dev.

also it might be considered impolite to send the same message
twice to mailinglist ;)

On 2/25/10 1:13 AM, zheng shi wrote:
> Hi,
> I'm wondering when /proc/cmdline has "root=/dev/mtdblockX",
> name_to_dev_t_real will return __makedev(0,254) for root device's
device
> number
> which is weired. I think we need to create the device on the fly from
> information in sysfs.
>
This dev_t is a special one internal to kinit that is used internally to 
special case mtdblock root command lines.  It's an implementation 
artifact that is a little confusing when looking at the output, but it 
should work..

I believe the use of /dev/mtdblockX requires the device node to be 
already present in the initramfs fwiw.
> Maybe I have mistaken something. Is there any clue?
>
> --
> Regards, Shizheng
>
>
>
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