[RFC v2 6/8] bootm: add kexec ELF support
Antony Pavlov
antonynpavlov at gmail.com
Wed Dec 7 23:29:32 PST 2016
On Wed, 7 Dec 2016 20:59:04 +0100
Sascha Hauer <s.hauer at pengutronix.de> wrote:
> On Mon, Dec 05, 2016 at 12:40:31PM +0300, Antony Pavlov wrote:
> > Also introduce reboot() for starting already loaded
> > via kexec ELF segments.
> >
> > Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
> > ---
> > include/linux/reboot.h | 14 ++++++++++++++
> > lib/kexec/Makefile | 1 +
> > lib/kexec/kexec-bootm-elf.c | 37 +++++++++++++++++++++++++++++++++++++
> > 3 files changed, 52 insertions(+)
> >
> > diff --git a/include/linux/reboot.h b/include/linux/reboot.h
> > new file mode 100644
> > index 0000000..454ed33
> > --- /dev/null
> > +++ b/include/linux/reboot.h
> > @@ -0,0 +1,14 @@
> > +#ifndef _LINUX_REBOOT_H
> > +#define _LINUX_REBOOT_H
> > +
> > +/*
> > + * Commands accepted by the _reboot() system call.
> > + *
> > + * KEXEC Restart system using a previously loaded Linux kernel
> > + */
> > +
> > +#define LINUX_REBOOT_CMD_KEXEC 0x45584543
> > +
> > +extern int reboot(int cmd);
> > +
> > +#endif /* _LINUX_REBOOT_H */
> > diff --git a/lib/kexec/Makefile b/lib/kexec/Makefile
> > index 8febef1..2f3dc1d 100644
> > --- a/lib/kexec/Makefile
> > +++ b/lib/kexec/Makefile
> > @@ -1,3 +1,4 @@
> > obj-y += kexec.o
> > obj-y += kexec-elf.o
> > obj-y += kexec-elf-exec.o
> > +obj-y += kexec-bootm-elf.o
> > diff --git a/lib/kexec/kexec-bootm-elf.c b/lib/kexec/kexec-bootm-elf.c
> > new file mode 100644
> > index 0000000..ceef6c7
> > --- /dev/null
> > +++ b/lib/kexec/kexec-bootm-elf.c
> > @@ -0,0 +1,37 @@
> > +#include <bootm.h>
> > +#include <init.h>
> > +#include <binfmt.h>
> > +#include <errno.h>
> > +#include <linux/reboot.h>
> > +#include <environment.h>
> > +
> > +#include "kexec.h"
> > +
> > +static int do_bootm_elf(struct image_data *data)
> > +{
> > + kexec_load_file(data->os_file, 0);
> > + setenv("global.bootm.image", data->os_file);
> > + reboot(LINUX_REBOOT_CMD_KEXEC);
> > +
> > + return -ERESTARTSYS;
> > +}
> > +
> > +static struct image_handler elf_handler = {
> > + .name = "ELF",
> > + .bootm = do_bootm_elf,
> > + .filetype = filetype_elf,
> > +};
> > +
> > +static struct binfmt_hook binfmt_elf_hook = {
> > + .type = filetype_elf,
> > + .exec = "bootm",
> > +};
> > +
> > +static int elf_register_image_handler(void)
> > +{
> > + register_image_handler(&elf_handler);
> > + binfmt_register(&binfmt_elf_hook);
> > +
> > + return 0;
> > +}
> > +late_initcall(elf_register_image_handler);
>
> The code needed to actually start a kexec kernel is architecture
> specific, so the registration of the ELF handler should be done by this
> architecture specific code. Then you also don't need this awkward reboot()
> stuff. I'm thinking of a
>
> int bootm_register_kexec_handler(int (*do_bootm)(struct image_data *data));
>
> to be called by MIPS or malta specific code.
>
Moreover current RFC v2 kexec patchseries contains too many redundant code
(e.g. kexec uses it's own filetype-like infrastructure).
I agree. Current barebox kexec infrastructure is used only for MIPS so I can move
some code from lib/ to arch/mips.
--
Best regards,
Antony Pavlov
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