[Buildroot] Antw: Re: Antw: Re: How to get the kernel to mount a rootfs without an initramfs ??

[Buildroot] Antw: Re: Antw: Re: How to get the kernel to mount a rootfs without an initramfs ??

[Jeremy Rosen]

> 
> the kernel panic message is the following:
> 
> VFS: Cannot open root device "mmcblk0" or unknow-block(0,0) Please
> append a correct "root=" boot option; here are the available
> partitions: not syncing: VFS: Unable to mount root fs on
> unknown-block(0,0)
> 
> As far as I know I have never partitioned the SD at all, so I don't
> think p1 is important then. Maybe it's easier if you can send me
> your command line , so I know what's the "truth" and look up what
> went wrong here
> 


well, I don't understand where is your rootfs, then... do you have
a single partition on the SD ? you do need to have a partition 
table afaik, even for a single partition. 

Try to partition your SD card with a partition editor and then 
adding the squashfs as the first partition

[Buildroot] Antw: Re: Antw: Re: How to get the kernel to mount a rootfs without an initramfs ??

[Arnout Vandecappelle]

On 11/02/14 10:53, Jeremy Rosen wrote:
>>
>> the kernel panic message is the following:
>>
>> VFS: Cannot open root device "mmcblk0" or unknow-block(0,0) Please
>> append a correct "root=" boot option; here are the available
>> partitions: not syncing: VFS: Unable to mount root fs on
>> unknown-block(0,0)

 Actually this sounds like you have no mmc driver in your kernel.

 Regards,
 Arnout

>>
>> As far as I know I have never partitioned the SD at all, so I don't
>> think p1 is important then. Maybe it's easier if you can send me
>> your command line , so I know what's the "truth" and look up what
>> went wrong here
>>
> 
> 
> well, I don't understand where is your rootfs, then... do you have
> a single partition on the SD ? you do need to have a partition 
> table afaik, even for a single partition. 
> 
> Try to partition your SD card with a partition editor and then 
> adding the squashfs as the first partition
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> buildroot mailing list
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> 
> 


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

[Buildroot] Antw: Re: Antw: Re: Antw: Re: How to get the kernel to mount a rootfs without an initramfs ??

[Frank Ihle]

>Actually this sounds like you have no mmc driver in your kernel.

I'm using the defconfig where 

in make linux-menuconfig is selected the following:

+Device Drivers
 <*> MMC/SD/SDIO card support
+ + <*> MMC block device driver
+ + <*> MMC host test driver
+ + <*> Atmel SD/MMC Driver (Atmel Multimedia Card Interface support)
+ + [ * ] Atmel MCI DMA support (Exp.)

well but now, that you mention it, it's weired. When I do a bootable image with this settings but with initramfs and busybox as init system then I should be able to see which devices are detected, right? So If I do ls /dev/ mmcblk or sdb isn't even in the list, is that a normal behaviour?


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[Buildroot] Antw: Re: Antw: Re: Antw: Re: How to get the kernel to mount a rootfs without an initramfs ??

[Arnout Vandecappelle]

On 12/02/14 09:05, Frank Ihle wrote:
>>Actually this sounds like you have no mmc driver in your kernel.
> 
> I'm using the defconfig where
> 
> in make linux-menuconfig is selected the following:
> 
> +Device Drivers
>  <*> MMC/SD/SDIO card support
> + + <*> MMC block device driver
> + + <*> MMC host test driver
> + + <*> Atmel SD/MMC Driver (Atmel Multimedia Card Interface support)
> + + [ * ] Atmel MCI DMA support (Exp.)
> 
> well but now, that you mention it, it's weired. When I do a bootable
> image with this settings but with initramfs and busybox as init system
> then I should be able to see which devices are detected, right? So If I
> do ls /dev/ mmcblk or sdb isn't even in the list, is that a normal behaviour?

 No, it's not.

 The platform bindings may be missing in your board file.

 Which board are you building for? A standard board or a custom one? In
the latter case, you should check with your kernel developer where to
find the MMC device.

 Regards,
 Arnout


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

[Buildroot] Antw: Re: Antw: Re: Antw: Re: How to get the kernel to mount a rootfs without an initramfs ??

[Jeremy Rosen]

> 
> Well I'll try, but why then is the initramfs working? the only files
> i got on a sd is the boot.bin, u-boot.bin and kernel.bin (with
> initramfs) and I'm using this on a SD card as it came from the
> factory and it's working. I'll try the trick with partition the sd
> card now, let's see if that helps.
> 

if you got files on the SD then your SD is partitioned and has a single
FAT partition. I'm not sure where you put your squash fs... as an image
file on the SD card (i.e on the FAT partition of the SD card )