> On Wednesday 14 October 2015 10:18:47 Huan Wang wrote: > > > On Thursday 24 September 2015 07:27:10 Huan Wang wrote: > > > > > On Fri, Sep 18, 2015 at 4:38 AM, Huan Wang > > > > > <alison.w...@freescale.com> > > > > > wrote: > > > > > > > > > > > [Alison Wang] Thanks for your reply. I agreed with you about > > > > > > creating a new multi_v7_lpae_defconfig. In > > > > > > multi_v7_lpae_defconfig, I need to add the following CONFIG_XX > > > > > > to support LS1021A based on > > > > > multi_v7_defconfig. > > > > > > > > > > > > CONFIG_ARM_LPAE=y > > > > > > CONFIG_VMSPLIT_2G=y > > > > > > > > > > Is CONFIG_VMSPLIT_2G=y really needed? > > > > [Alison Wang] I tried to remove CONFIG_VMSPLIT_2G and used the > > > > default CONFIG_VMSPLIT_3G, but kernel could not boot up. It hangs > > > > at " Starting > > > kernel ... ". > > > > > > > > Any suggestion? Thanks. > > > > > > Try enabling DEBUG_LL for your platform to get some debug output, if > > > you still don't get any helpful messages, try also inserting > > > > > > printascii(__func__); > > > > > > statements in the early boot process to see how far you get before the > hang. > > > > > [Alison Wang] I can get to __turn_mmu_on or later, but I could not get > > the print message "Booting Linux on physical CPU 0xf00" in > smp_setup_processor_id(). > > > > I guess something wrong with the initial page tables in > > __create_page_tables, as for CONFIG_VMSPLIT_3G, only PAGE_OFFSET is > changed from 0x80000000 to 0xC0000000. > > BTW, on our platform, TEXT_OFFSET is 0x00008000, PHYS_OFFSET is > 0x80000000. > > > > Any suggestion? Thanks. > > My first guess is that there is something wrong with your debug_ll > implementation, as that would explain why you can't get anything to the > console after turning on page tables. > > It looks like ls1021a uses lpuart, but I can't even see an implementation > for that in arch/arm/include/debug/. What code do you use for printing? > [Alison Wang] ls1021a uses duart as the default serial port, not lpuart. So 8250/16550 serial driver is used. Let me explain my debug process in detail.
When CONFIG_VMSPLIT_2G is used, I could boot up the whole kernel and get the print message " Booting Linux on physical CPU 0xf00" after "Starting kernel" as below. Starting kernel ... [ 0.000000] Booting Linux on physical CPU 0xf00 ..... But when CONFIG_VMSPLIT_3G is used, I couldn't get print message " Booting Linux on physical CPU 0xf00". It only hangs at "Starting kernel ...". Moreover, I add some asm code in __turn_mmu_on to print some simple characters, and I could get the print characters when CONFIG_VMSPLIT_3G is used. So I guess there is something wrong with the page tables. Best Regards, Alison Wang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
