Re: [Qemu-devel] [PATCH] fix entry pointer for ELF kernels loaded with -kernel option

[Kevin Wolf <kwolf@redhat.com>]

Am 05.09.2012 11:05, schrieb Henning Schild:
>  This patch fixes a bug in qemu which prevents Multiboot ELF kernels 
>  from being loaded with the -kernel option. Find a full description of 
>  the problem here https://bugs.launchpad.net/qemu/+bug/1044727 .

The logic looks good to me, but there are a few points about the patch
itself (see http://wiki.qemu.org/Contribute/SubmitAPatch).

First thing is that the patch needs a proper Signed-off-by line. This is
absolutely crucial. The other points could be fixed manually by a
potential patient enough maintainer, but you are the only one who can
provide the Signed-off-by. Without it, the patch won't be applied.

>  ---
>   hw/elf_ops.h |   10 ++++++++++
>   1 files changed, 10 insertions(+), 0 deletions(-)
> 
>  diff --git a/hw/elf_ops.h b/hw/elf_ops.h
>  index fa65ce2..aeddd11 100644
>  --- a/hw/elf_ops.h
>  +++ b/hw/elf_ops.h
>  @@ -269,6 +269,16 @@ static int glue(load_elf, SZ)(const char *name, 
>  int fd,

The patch is corrupted by line wraps. Using git format-patch/send-email
avoids this kind of problems. Alternatively, attach the patch in
addition so that an uncorrupted version can be used for applying it.

>                   addr = ph->p_paddr;
>               }
>  
>  +            /* the entry pointer in the ELF header is a virtual
>  +             * address, if the text segments paddr and vaddr differ
>  +             * we need to adjust the entry */
>  +            if (pentry && !translate_fn &&
>  +                ph->p_vaddr != ph->p_paddr &&
>  +                ehdr.e_entry >= ph->p_vaddr &&
>  +                ehdr.e_entry < ph->p_vaddr + ph->p_filesz &&
>  +                ph->p_flags & PF_X)
>  +                    *pentry = ehdr.e_entry - ph->p_vaddr + 
>  ph->p_paddr;

The coding style problem that was already mentioned. qemu puts braces
even for single statements.

Kevin