Hi Felix,

I saw your mail regarding your attempt to make ext4 filesystem images from 
IMAGE_CMD:ext4 reproducible. 
If you don't mind, could you briefly explain what was the problem you faced 
in achieving this? 
I am also trying to understand on how to achieve the same.

Thanks and Regards,
Adithya Balakumar


On Tuesday, April 23, 2024 at 2:47:11 PM UTC+5:30 MOESSBAUER, Felix wrote:

On Thu, 2023-12-07 at 21:11 +0530, venkat...@toshiba-tsip.com wrote: 
> From: venkata pyla <venkat...@toshiba-tsip.com> 
> 
> E2FSPROGS_FAKE_TIME: sets fixed times for the inodes in the file 
> system. 
> hash_seed: creates reproducible directory indexes in the file system. 
> 
> Reference commit in e2fsprogs: 
> e1f7100643a46456be107b33098f6034b0835e6d 
> 
> Signed-off-by: venkata pyla <venkat...@toshiba-tsip.com> 
> --- 
>  scripts/lib/wic/partition.py | 11 +++++++++++ 
>  1 file changed, 11 insertions(+) 
> 
> diff --git a/scripts/lib/wic/partition.py 
> b/scripts/lib/wic/partition.py 
> index e50871b8..90b2c037 100644 
> --- a/scripts/lib/wic/partition.py 
> +++ b/scripts/lib/wic/partition.py 
> @@ -280,6 +280,17 @@ class Partition(): 
>   
>          extraopts = self.mkfs_extraopts or "-F -i 8192" 
>   
> +        if os.getenv('SOURCE_DATE_EPOCH'): 
> +            sde_time = int(os.getenv('SOURCE_DATE_EPOCH')) 
> +            pseudo = "export E2FSPROGS_FAKE_TIME=%s;%s" % (sde_time, 
> pseudo) 
> + 
> +            # Set hash_seed to generate deterministic directory 
> indexes 
> +            namespace = uuid.UUID("e7429877-e7b3-4a68-a5c9- 
> 2f2fdf33d460") 
> +            if self.fsuuid: 
> +                namespace = uuid.UUID(self.fsuuid) 
> +            hash_seed = str(uuid.uuid5(namespace, str(sde_time))) 
> +            extraopts += " -E hash_seed=%s" % hash_seed 
> + 

Hi, while reworking the SDE in ISAR, I stumbled upon this as well. 
This patch only covers the .wic part, but we need a similar patch for 
the IMAGE_CMD:ext4 as well. I tried to mimic the pattern there, but I 
was not able to make the .ext4 build reproducible (the diff indicated 
that the inodes are still shuffled around). This makes me wonder if 
mke2fs.ext4 even supports producing a reproducible rootfs. 

Have you been able to create a bit-by-bit identical .wic of an ext4 
partition? 

Best regards, 
Felix 

>          label_str = "" 
>          if self.label: 
>              label_str = "-L %s" % self.label 

-- 
Siemens AG, Technology 
Linux Expert Center 


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