[U-Boot] [PATCH] PowerPC MPC85xx: don't hang on read exception

[Liu Dave-R63238]

> Set HID1[RFXE] = 1 in cpu/mpc85xx/start.S.  When this bit is 0, any
> condition that asserts the internal core_fault_in* signal will result
> in a processor hang, recoverable only with reset.  When this bit is 1,
> such a condition will cause a machine check exception and software
> will have a chance to print an error message.
> 
> Conditions that can assert core_fault_in* include ECM local access
> error (read an unmapped target address), multi-bit ECC error in L2
> cache or DDR RAM, localbus parity error, and a variety of PCI errors.
> 
> A long discussion of why this bit must be set can be found in, among
> other places, the "MPC8548E PowerQUICC III Integrated Processor Family
> Reference Manual" section 6.10.2, table 6-19 "HID1 Field
> Descriptions."  It says that leaving the bit 0 "is not a recommended
> configuration.  The processor may stall indefinitely due to an
> unreported error."
> 
> We have tested the use of this bit for two years, both in u-boot/Linux
> and in a proprietary operating system, in systems using MPC8541,
> MPC8545/8, and MPC8536.

Why not use the interrupt mode?
If you use that mode, it will get more valuable information. Currently,
U-boot have a little bit error detection mechanism if you configure
the interrupts and enable the error interrupts.

Thanks, Dave