On Tue, 13 Sep 2011 15:26:37 +0200
Michael Holzheu <holzheu at linux.vnet.ibm.com> wrote:
> From: Michael Holzheu <holzheu at linux.vnet.ibm.com>
>
> This patch implements the crash_map_pages() function for s390.
> KEXEC_CRASH_MEM_ALIGN is set to HPAGE_SIZE, in order to support
> kernel mappings that use large pages.
>
> Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> ---
> arch/s390/include/asm/kexec.h | 3 +++
> arch/s390/kernel/machine_kexec.c | 31 +++++++++++++++++++++++++++++++
> arch/s390/kernel/setup.c | 10 ++++++----
> 3 files changed, 40 insertions(+), 4 deletions(-)
>
> --- a/arch/s390/include/asm/kexec.h
> +++ b/arch/s390/include/asm/kexec.h
> @@ -36,6 +36,9 @@
> /* Allocate one page for the pdp and the second for the code */
> #define KEXEC_CONTROL_PAGE_SIZE 4096
>
> +/* Alignment of crashkernel memory */
> +#define KEXEC_CRASH_MEM_ALIGN HPAGE_SIZE
Why not make this unconditional, for all architectures which support
hugepages? ie:
#ifdef HPAGE_SIZE
#define KEXEC_CRASH_MEM_ALIGN HPAGE_SIZE
#else
#define KEXEC_CRASH_MEM_ALIGN PAGE_SIZE
#endif
in include/linux/kexec.h?
IOW, what are the compromises here?
Also, does s390 support CONFIG_HUGETLB_PAGE=n? If so, does the use of
HPAGE_SIZE still make sense? Does it compile?
> /* The native architecture */
> #define KEXEC_ARCH KEXEC_ARCH_S390
>
> --- a/arch/s390/kernel/machine_kexec.c
> +++ b/arch/s390/kernel/machine_kexec.c
> @@ -243,6 +243,37 @@ static void __machine_kdump(void *image)
> #endif
>
> /*
> + * Map or unmap crashkernel memory
> + */
> +static void crash_map_pages(int enable)
> +{
> + unsigned long size = crashk_res.end - crashk_res.start + 1;
resource_size().
> + BUG_ON(crashk_res.start % KEXEC_CRASH_MEM_ALIGN ||
> + size % KEXEC_CRASH_MEM_ALIGN);
> + if (enable)
> + vmem_add_mapping(crashk_res.start, size);
> + else
> + vmem_remove_mapping(crashk_res.start, size);
> +}
>
> ...
>
