On Wed, 12 Oct 2016 18:35:21 +1100
Balbir Singh <bsinghar...@gmail.com> wrote:
> On 12/10/16 17:57, Nicholas Piggin wrote:
> > This adds a config option that can help exercise the case when
> > the kernel is not running at PAGE_OFFSET.
> >
> > Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> > ---
> > arch/powerpc/Kconfig | 9 +++++++++
> > arch/powerpc/kernel/head_64.S | 4 ++++
> > arch/powerpc/kernel/setup-common.c | 3 +++
> > 3 files changed, 16 insertions(+)
> >
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index 65fba4c..5d43cb8 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -478,6 +478,15 @@ config RELOCATABLE
> > setting can still be useful to bootwrappers that need to know the
> > load address of the kernel (eg. u-boot/mkimage).
> >
> > +config RELOCATABLE_TEST
> > + bool "Test relocatable kernel"
> > + depends on (PPC64 && RELOCATABLE)
> > + default n
> > + help
> > + This runs the relocatable kernel at the address it was initially
> > + loaded at, which tends to be non-zero and therefore test the
> > + relocation code.
> > +
> > config CRASH_DUMP
> > bool "Build a kdump crash kernel"
> > depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
> > diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> > index 79da0641..bc9ceac 100644
> > --- a/arch/powerpc/kernel/head_64.S
> > +++ b/arch/powerpc/kernel/head_64.S
> > @@ -111,8 +111,12 @@ __secondary_hold_acknowledge:
> > .globl __run_at_load
> > __run_at_load:
> > DEFINE_FIXED_SYMBOL(__run_at_load)
> > +#ifdef CONFIG_RELOCATABLE_TEST
> > + .long 0x1 /* Test relocation, do not relocate to 0 */
> > +#else
> > .long 0x72756e30 /* "run0" -- relocate to 0 by default */
> > #endif
> > +#endif
>
> Could we do something like
>
> config RELOCATION_VALUE
> default 0x72756e30
> default 1 if CONFIG_RELOCTABLE_TEST
>
> and then get
>
> .long CONFIG_RELOCATION_VALUE
Normally I'm up for reducing ifdefs in S and c files, but in this case
I'm not sure. I like being able to see the two possible values in the
source. I don't really mind though. If you or Michael feel strongly, I'm
happy to change it.
> > . = 0x60
> > /*
> > diff --git a/arch/powerpc/kernel/setup-common.c
> > b/arch/powerpc/kernel/setup-common.c
> > index dba265c..18e0f19 100644
> > --- a/arch/powerpc/kernel/setup-common.c
> > +++ b/arch/powerpc/kernel/setup-common.c
> > @@ -795,6 +795,9 @@ static __init void print_system_info(void)
> > pr_info("mmu_features = 0x%08x\n", cur_cpu_spec->mmu_features);
> > #ifdef CONFIG_PPC64
> > pr_info("firmware_features = 0x%016lx\n", powerpc_firmware_features);
> > +
> > + if (get_paca()->kernelbase != PAGE_OFFSET)
> > + pr_info("kernelbase = 0x%llx\n", get_paca()->kernelbase);
> > #endif
> >
>
> Do we need this? We get physical_offset if we are relocated.
You're right, that hunk can go.
Thanks,
Nick
