[Buildroot] Is there a way to automatically detect the minimum required BR2_TARGET_ROOTFS_EXT2_SIZE?

Ciro Santilli ciro.santilli at gmail.com
Sun Mar 11 09:57:58 UTC 2018


On Sat, Mar 10, 2018 at 8:58 PM, Yann E. MORIN <yann.morin.1998 at free.fr> wrote:
> Ciro, All,
>
> On 2018-03-10 16:14 +0000, Ciro Santilli spake thusly:
>> https://stackoverflow.com/questions/49211241/is-there-a-way-to-automatically-detect-the-minimum-required-br2-target-rootfs-ex
>>
>> I'm when making a big non-embedded image, I keep hitting the error:
>>
>>     *** Maybe you need to increase the filesystem size
>> (BR2_TARGET_ROOTFS_EXT2_SIZE)
>>
>> and then I have to do a `du` on `output/target` to find out how big I
>> have to make `BR2_TARGET_ROOTFS_EXT2_SIZE`.
>>
>> Is there a way to automate this, or a decent workaround?
>
> No, becaaue it is not reliable, see commit:
>
>     c6bca8cef fs/ext2: Remove support for auto-calculation of rootfs size
>
> In the end, it does nto make sense to do auto-calculation, because on an
> embedded device, you have to now the layout and size of your storage.
> So, you know what size you want your ext filesystem to be.
>

Thanks for the info.

I'm considering using Buildroot to get clean neat images for emulation
applications (like learn Linux kernel, benchmark some stuff on gem5),
but since it is not possible to do it reliably, I will use another
method instead of ext2 images.

> Regards,
> Yann E. MORIN.
>
>> Some workarounds I'm considering:
>>
>> * put the big stuff under 9p:
>> https://superuser.com/questions/628169/how-to-share-a-directory-with-the-host-without-networking-in-qemu
>> * use CPIO and `-initrd`
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>
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