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https://issues.apache.org/jira/browse/MYNEWT-670?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Christopher Collins updated MYNEWT-670:
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    Description: 
Currently, the largest image or file chunk that a Mynewt device can receive is 
hardcoded at 400 bytes.  Furthermore, the largets CBOR attribute that we can 
decode is 300 bytes long.This is not great because this number is independent 
of the transport MTU, so the client has no way of knowing the limit.

The fix is to create three new compile-time settings:
* CBORATTR_MAX_SIZE
* FS_UPLOAD_MAX_CHUNK_SIZE
* IMGMGR_MAX_CHUNK_SIZE

and set them to 512 by default.  This value is large enough to accommodate 
full-size BLE packets.

This is still not a perfect solution because these values are not tied to the 
MTU in any way.  One way to truly solve this would be to have an "NMP MTU" that 
the client can discover.  That would be a pretty big change.

  was:
Currently, the largest image or file chunk that a Mynewt device can receive is 
hardcoded at 400 bytes.  This is not great because this number is independent 
of the transport MTU, so the client has no way of knowing the limit.

The fix is to create two new compile-time settings:
* FS_UPLOAD_MAX_CHUNK_SIZE
* IMGMGR_MAX_CHUNK_SIZE

and set them to 512 by default.  This value is large enough to accommodate 
full-size BLE packets.

This is still not a perfect solution because these values are not tied to the 
MTU in any way.  One way to truly solve this would be to have an "NMP MTU" that 
the client can discover.  That would be a pretty big change.

        Summary: NMP: Make max chunk size configurable  (was: image / fs NMP: 
Make max chunk size configurable)

> NMP: Make max chunk size configurable
> -------------------------------------
>
>                 Key: MYNEWT-670
>                 URL: https://issues.apache.org/jira/browse/MYNEWT-670
>             Project: Mynewt
>          Issue Type: Improvement
>          Components: Newtmgr
>            Reporter: Christopher Collins
>            Assignee: Christopher Collins
>             Fix For: v1_1_0_rel
>
>
> Currently, the largest image or file chunk that a Mynewt device can receive 
> is hardcoded at 400 bytes.  Furthermore, the largets CBOR attribute that we 
> can decode is 300 bytes long.This is not great because this number is 
> independent of the transport MTU, so the client has no way of knowing the 
> limit.
> The fix is to create three new compile-time settings:
> * CBORATTR_MAX_SIZE
> * FS_UPLOAD_MAX_CHUNK_SIZE
> * IMGMGR_MAX_CHUNK_SIZE
> and set them to 512 by default.  This value is large enough to accommodate 
> full-size BLE packets.
> This is still not a perfect solution because these values are not tied to the 
> MTU in any way.  One way to truly solve this would be to have an "NMP MTU" 
> that the client can discover.  That would be a pretty big change.



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