On 11/13/13 at 03:50pm, Matt Fleming wrote:
> On Tue, 05 Nov, at 04:20:12PM, dyoung at redhat.com wrote:
> > kexec kernel will need exactly same mapping for
> > efi runtime memory ranges. Thus here export the
> > runtime ranges mapping to sysfs, kexec-tools
> > will assemble them and pass to 2nd kernel via
> > setup_data.
> >
> > Introducing a new directly /sys/firmware/efi/efi-runtime-map
> > Just like /sys/firmware/memmap. Containing below attribute
> > in each file of that directory:
> > attribute num_pages phys_addr type virt_addr
> >
> > It will not work for efi 32bit. Only x86_64 currently.
> >
> > Signed-off-by: Dave Young <dyoung at redhat.com>
> > ---
> > Documentation/ABI/testing/sysfs-efi-runtime-map | 45 ++++++
> > arch/x86/include/asm/efi.h | 3
> > arch/x86/platform/efi/efi.c | 11 +
> > drivers/firmware/efi/Kconfig | 10 +
> > drivers/firmware/efi/Makefile | 1
> > drivers/firmware/efi/efi-runtime-map.c | 164 ++++++++++++++++++++++++
> > drivers/firmware/efi/efi.c | 3
> > include/linux/efi.h | 6
> > 8 files changed, 242 insertions(+), 1 deletion(-)
>
> [...]
>
> > @@ -852,6 +855,14 @@ static void efi_map_regions(void **new_m
> >
> > memcpy(*new_memmap + (*count * memmap.desc_size), md,
> > memmap.desc_size);
> > + if (md->type != EFI_BOOT_SERVICES_CODE &&
> > + md->type != EFI_BOOT_SERVICES_DATA) {
> > + efi_runtime_map = krealloc(efi_runtime_map,
> > + (nr_efi_runtime_map + 1) *
> > + sizeof(efi_memory_desc_t), GFP_KERNEL);
> > + *(efi_runtime_map + nr_efi_runtime_map) = *md;
> > + nr_efi_runtime_map++;
> > + }
> > (*count)++;
> > }
>
> You really need to be using 'memmap.desc_size' here and not
> sizeof(efi_memory_desc_t) as the two may differ. Also, you should be
> checking for failure of krealloc() and using memcpy() instead of
> directly dereferencing 'md'.
I'm a bit confused with the desc_size and sizeof(efi_memory_desc_t),
Because I intended to same struct efi_memory_desc_t in userspace to pass the
setup_data, so I worry about if desc_size will cause problems.
Will double check it.
>
> > --- linux-2.6.orig/drivers/firmware/efi/Makefile
> > +++ linux-2.6/drivers/firmware/efi/Makefile
> > @@ -4,3 +4,4 @@
> > obj-y += efi.o vars.o
> > obj-$(CONFIG_EFI_VARS) += efivars.o
> > obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o
> > +obj-$(CONFIG_EFI_RUNTIME_MAP) += efi-runtime-map.o
> > --- /dev/null
> > +++ linux-2.6/drivers/firmware/efi/efi-runtime-map.c
>
> Small nit but I wouldn't bother prefixing the filename with "efi-",
> since you can't build this file as a module.
Ok, will do
>
> > +/*
> > + * These are default attributes that are added for every memmap entry.
> > + */
> > +static struct attribute *def_attrs[] = {
> > + &map_type_attr.attr,
> > + &map_phys_addr_attr.attr,
> > + &map_virt_addr_attr.attr,
> > + &map_num_pages_attr.attr,
> > + &map_attribute_attr.attr,
> > + NULL
> > +};
>
> If the UEFI spec ever releases an update for the memory descriptor
> structure, and bumps 'memmap.desc_version', how are we going to signal
> the incompatibility to legacy versions of kexec tools?
Hmm, that is a problem. I will consider to export memmap according to
what firmware provided with extra desc_version instead of using attrs from kernel
data structure efi_memory_desc_t
Now it's clear for previous question about desc_size and sizeof(efi_memory_desc_t)
Will switch to use desc_size.
>
> --
> Matt Fleming, Intel Open Source Technology Center
