Hi, Thanks all for quick response.
Actually we are having a huge application for video capture which is presently running on x86 based board having some DSPs. As per the data sheet of MPC8349E(e300 core), MPC8349E can be configured in true little endian mode.
So, if we are able to configure MPC8349E(e300 core) in true little endian mode, we can utilize our huge x86 based application on MPC8349E. That is why we want to know whether MPC8349E(e300 core) is tested on true little endian mode till now..?
If it has been tested in true little endian mode what are the necessary settings in U-Boot except RCWH change, LE bit field in MSR register and LET bit field in HID2 register.
If MPC8349E(e300 core) is not tested in true little endian mode till now, what could be the reason ..? What are the drawbacks/problems we could face during the little endian configuration of MPC8349E(e300-core)..?
Please give your suggestions/comments on this. Any help/comment will be appreciated.
Thanks, Vivek Trivedi
We want to configure MPC8349E in little endian as some other PCI devices(DSPs) are operating in little endian.
Why should the fact that the DSPs over PCI being little endian impact how you run the 8349? All the u-boot and linux drivers deal with this for every PCI device I'm aware of and run the 8349 (and all PowerPC chips) in big-endian mode.
All access to the PCI device registers are wrapped in functions that do the proper byte swapping for you.
- k
-----Original Message----- From: Vivek Trivedi (WT01 - Embedded & Product Engineering) Sent: Friday, May 02, 2008 11:45 AM To: Vivek Trivedi (WT01 - Embedded & Product Engineering); 'u-boot-users@lists.sourceforge.net' Cc: 'kim.phillips@freescale.com' Subject: RE: Configuring U-Boot for MPC8349E in little endian mode
Hi, Thanks all for quick response.
Sorry, I forgot to tell that we are using MPC8349E processor with a "e300 core". And it is clearly mentioned in the e300 core datasheet that, it supports "True little-endian mode for compatibility with other true little-endian devices".
So, according to data sheet I have done following changes in U-Boot to configure it in true little endian mode: RCWH for little endian mode and enable the Little-endian mode in e300 core registers MSR bit LE and HID2 registers bit LET.
After doing these settings core is able to fetch RCW from flash and execute some assembly code in Start.S. But I am not able to understand why e300 core(i.e. MPC8349E in True) is not executing branch instruction(b , bl) only and jumping to alignment exception vector handler(0x600).
Do, I need to enable some -m alignment flag in U-Boot build so that e300-core can execute branch instructions. Is the e300-core is not able to interpret branch instruction(b , bl) in true little endian mode...?
Has any one tried to configure and run U-Boot for MPC8349E processor(e300 core) in true little endian mode...? Are missing any other setting in U-Boot for little endian operation...?
We want to configure MPC8349E in little endian as some other PCI devices(DSPs) are operating in little endian.
Any help/suggestion will be appreciated.
Thanks, Vivek Trivedi
In message 47230CE166B64744B0120173E4C2161E04D531CF@BLR-EC-MBX01.wipro.com you wrote:
We are using MPC8349E based board in big endian mode. It is working fine with U-Boot 1.1.3 .
Yes. Big endian is the natural byte order for PowerPC.
Now due to some reason we have to configure 8349E in little endian
mode.
Don't. You're on the road to trouble. Stop now.
Figure out what "some reason" is, and how to solve it differently, i. e. in a sane way.
Best regards,
Wolfgang Denk