- Forums
- Product Forums
- General Purpose MicrocontrollersGeneral Purpose Microcontrollers
- i.MX Forumsi.MX Forums
- QorIQ Processing PlatformsQorIQ Processing Platforms
- Identification and SecurityIdentification and Security
- Power ManagementPower Management
- MCX Microcontrollers
- S32G
- S32K
- S32V
- MPC5xxx
- Other NXP Products
- Wireless Connectivity
- S12 / MagniV Microcontrollers
- Powertrain and Electrification Analog Drivers
- Sensors
- Vybrid Processors
- Digital Signal Controllers
- 8-bit Microcontrollers
- ColdFire/68K Microcontrollers and Processors
- PowerQUICC Processors
- OSBDM and TBDML
- S32M
-
- Solution Forums
- Software Forums
- MCUXpresso Software and ToolsMCUXpresso Software and Tools
- CodeWarriorCodeWarrior
- MQX Software SolutionsMQX Software Solutions
- Model-Based Design Toolbox (MBDT)Model-Based Design Toolbox (MBDT)
- FreeMASTER
- eIQ Machine Learning Software
- Embedded Software and Tools Clinic
- S32 SDK
- S32 Design Studio
- GUI Guider
- Zephyr Project
- Voice Technology
- Application Software Packs
- Secure Provisioning SDK (SPSDK)
- Processor Expert Software
- MCUXpresso Training Hub
-
- Topics
- Mobile Robotics - Drones and RoversMobile Robotics - Drones and Rovers
- NXP Training ContentNXP Training Content
- University ProgramsUniversity Programs
- Rapid IoT
- NXP Designs
- SafeAssure-Community
- OSS Security & Maintenance
- Using Our Community
-
- Cloud Lab Forums
-
- Knowledge Bases
- ARM Microcontrollers
- i.MX Processors
- Identification and Security
- Model-Based Design Toolbox (MBDT)
- QorIQ Processing Platforms
- S32 Automotive Processing Platform
- Wireless Connectivity
- CodeWarrior
- MCUXpresso Suite of Software and Tools
- MQX Software Solutions
-
- Home
- :
- i.MX Processors
- :
- i.MX Processors Knowledge Base
- :
- Q&A: What is max size of uImage?
Q&A: What is max size of uImage?
- Subscribe to RSS Feed
- Mark as New
- Mark as Read
- Bookmark
- Subscribe
- Printer Friendly Page
- Report Inappropriate Content
Q&A: What is max size of uImage?
Q&A: What is max size of uImage?
Question:
In a single uImage to contain the compressed kernel and rootfs, if the uImage is greater than 16MB, the system will not boot and reports errors. Is there a size limitation on uImage? If so, is there a work around?
Answer:
uImage should only contains kernel compressed. rootfs should be read through a linux partition after the kernel boots up.
Regarding the uImage's size, there is no limitation. In the other hand, a single uImage with kernel and filesystem is needed; in other words, kernel (alias uImage) needs a filesystem to work, and these are two independent systems in that sense. If u-boot, kernel and filesystem are in a single device (SD Card), the filesystem must be mounted in the first partition (SD, eMMC, etc) starting somewhere > 16M/512 sectors.
But in cases where:
* A fast boot is needed with very small rootfs
* As a intermediate (temporal) rootfs before switching to the real rootfs. The usage (actually used when flashing with the MFG tool) of this intermediate system is to load heavy modules, keeping the uImage small.
This mechanism is called initramfs and the uImage will contain the kernel and the this mini rootfs compressed as cpio archive.
But there appears to be a 16MB limitation. See here: http://www.isysop.com/unpacking-and-repacking-u-boot-uimage-files/
It seems to be related to alignment suggesting that 24-bit addressing is used instead of 32-bit. I did notice Thumb mode is used, which seems odd to me.