Hi, I met some problems when reading sourcecode of u-boot 1.1.4 (for mpc85xx)

file /cpu/mpc85xx/start.s line 276

276. #if (CFG_CCSRBAR_DEFAULT != CFG_CCSRBAR) 277. /* Special sequence needed to update CCSRBAR itself */ 278. lis r4, CFG_CCSRBAR_DEFAULT@h 279. ori r4, r4, CFG_CCSRBAR_DEFAULT@l 280. 281. lis r5, CFG_CCSRBAR@h 282. ori r5, r5, CFG_CCSRBAR@l 283. srwi r6,r5,12 284. stw r6, 0(r4) 285. isync 286. 287. lis r5, 0xffff 288. ori r5,r5,0xf000 289. lwz r5, 0(r5) 290. isync 291. 292. lis r3, CFG_CCSRBAR@h 293. lwz r5, CFG_CCSRBAR@l(r3) 294. isync 295. #endif

I think it means if we don't use default CCSRBAR, we put the CCSRBAR addr actually used to the proper place in default CCSRBAR, so that it can jump to the addr we want to automatically.(line 276-286).

But, I don't know what line 287-294 does. Can some one tell me pls? Thanks for your help.