On 13 July 2013 04:57, Yadwinder Singh Brar <yadi.brar@xxxxxxxxxxx> wrote:
> Presently, using exynos_defconfig with CONFIG_DEBUG_LL and CONFIG_EARLY_PRINTK
> on, kernel is not booting, we are getting following:
>
> [ 0.000000] ------------[ cut here ]------------
> [ 0.000000] kernel BUG at mm/vmalloc.c:1134!
> [ 0.000000] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> [ 0.000000] Modules linked in:
> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 3.11.0-rc1 #633
> [ 0.000000] task: c052ec48 ti: c0524000 task.ti: c0524000
> [ 0.000000] PC is at vm_area_add_early+0x54/0x94
> [ 0.000000] LR is at add_static_vm_early+0xc/0x60
>
> Its because iotable_init tries to map UART again which is already mapped by
> debug_ll_io_init() call in exynos_init_io() within same virtal address range as
> requested later.
debug_ll_io_init ioremaps debug uart address space with 4KB size
whereas the exynos_init_io() function ioremaps a single 512KB memory
size for all the four uart ports which envelops the mapping created by
debug_ll_io_init. This is caught as a kernel bug.
>
> This issue seems to be occured after :
> commit ee4de5d99aeac44f4507b7538b2b3faedc5205b9
> ARM: 7781/1: mmu: Add debug_ll_io_init() mappings to early mappings
>
> This patch moves S3C_UART iodesc(in iodesc_list) inside CONFIG_DEBUG_LL check.
Instead of moving, all the such iodesc entries for UART controller can
be removed for all Samsung SoC's now since the Samsung uart driver
does a ioremap during probe and any needed iomapping for earlyprintk
is handled by debug_ll_io_init().
>
> Tested on 4412 and 5250 smdks.
>
> Signed-off-by: Yadwinder Singh Brar <yadi.brar@xxxxxxxxxxx>
> ---
> arch/arm/mach-exynos/common.c | 20 ++++++++++++++------
> 1 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/mach-exynos/common.c b/arch/arm/mach-exynos/common.c
> index 164685b..7f0591f 100644
> --- a/arch/arm/mach-exynos/common.c
> +++ b/arch/arm/mach-exynos/common.c
> @@ -150,11 +150,6 @@ static struct map_desc exynos4_iodesc[] __initdata = {
> .length = SZ_64K,
> .type = MT_DEVICE,
> }, {
> - .virtual = (unsigned long)S3C_VA_UART,
> - .pfn = __phys_to_pfn(EXYNOS4_PA_UART),
> - .length = SZ_512K,
> - .type = MT_DEVICE,
> - }, {
> .virtual = (unsigned long)S5P_VA_CMU,
> .pfn = __phys_to_pfn(EXYNOS4_PA_CMU),
> .length = SZ_128K,
> @@ -185,6 +180,14 @@ static struct map_desc exynos4_iodesc[] __initdata = {
> .length = SZ_4K,
> .type = MT_DEVICE,
> },
> +#ifndef CONFIG_DEBUG_LL
> + {
> + .virtual = (unsigned long)S3C_VA_UART,
> + .pfn = __phys_to_pfn(EXYNOS4_PA_UART),
> + .length = SZ_512K,
> + .type = MT_DEVICE,
> + },
> +#endif
> };
>
> static struct map_desc exynos4_iodesc0[] __initdata = {
> @@ -268,21 +271,26 @@ static struct map_desc exynos5_iodesc[] __initdata = {
> .pfn = __phys_to_pfn(EXYNOS5_PA_PMU),
> .length = SZ_64K,
> .type = MT_DEVICE,
> - }, {
> + },
> +#ifndef CONFIG_DEBUG_LL
> + {
> .virtual = (unsigned long)S3C_VA_UART,
> .pfn = __phys_to_pfn(EXYNOS5_PA_UART),
> .length = SZ_512K,
> .type = MT_DEVICE,
> },
> +#endif
> };
>
> static struct map_desc exynos5440_iodesc0[] __initdata = {
> +#ifndef CONFIG_DEBUG_LL
> {
> .virtual = (unsigned long)S3C_VA_UART,
> .pfn = __phys_to_pfn(EXYNOS5440_PA_UART0),
> .length = SZ_512K,
> .type = MT_DEVICE,
> },
> +#endif
> };
>
> void exynos4_restart(enum reboot_mode mode, const char *cmd)
> --
> 1.7.0.4
>
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