On Tue, Nov 8, 2022 at 8:37 AM Ard Biesheuvel <a...@kernel.org> wrote:
> On Tue, 8 Nov 2022 at 16:59, Daniel Kiper <dki...@net-space.pl> wrote:
> >
> > On Fri, Nov 04, 2022 at 04:26:06PM -0700, Atish Patra wrote:
> > > Update the RISC-V Linux kernel image headers as per the current header.
> > >
> > > Reference:
> > > <Linux kernel source>/Documentation/riscv/boot-image-header.rst
> > >
> > > 474efecb65dc: ("riscv: modify the Image header to improve
> compatibility with the ARM64 header")
> >
> > The latest commit which updates
> Documentation/riscv/boot-image-header.rst is
> > 1d5c17e47028 (RISC-V: Typo fixes in image header and documentation).
> >
> > > Acked-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
> > > Signed-off-by: Atish Patra <ati...@rivosinc.com>
> >
> > The order of these lines should be reversed...
> >
> > > ---
> > > include/grub/riscv32/linux.h | 19 ++++++++++---------
> > > include/grub/riscv64/linux.h | 19 +++++++++++--------
> > > 2 files changed, 21 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/include/grub/riscv32/linux.h
> b/include/grub/riscv32/linux.h
> > > index 512b777c8a41..a884d4f4760c 100644
> > > --- a/include/grub/riscv32/linux.h
> > > +++ b/include/grub/riscv32/linux.h
> > > @@ -19,21 +19,22 @@
> > > #ifndef GRUB_RISCV32_LINUX_HEADER
> > > #define GRUB_RISCV32_LINUX_HEADER 1
> > >
> > > -#define GRUB_LINUX_RISCV_MAGIC_SIGNATURE 0x52534356 /* 'RSCV' */
> > > -
> > > -/* From linux/Documentation/riscv/booting.txt */
> > > +/* From linux/Documentation/riscv/boot-image-header.rst */
> > > struct linux_riscv_kernel_header
> > > {
> > > grub_uint32_t code0; /* Executable code */
> > > grub_uint32_t code1; /* Executable code */
> > > - grub_uint64_t text_offset; /* Image load offset */
> > > - grub_uint64_t res0; /* reserved */
> > > - grub_uint64_t res1; /* reserved */
> > > + grub_uint64_t text_offset; /* Image load offset, little endian */
> > > + grub_uint64_t image_size; /* Effective Image size, little endian */
> > > + grub_uint64_t flags; /* kernel flags, little endian */
> > > + grub_uint32_t version; /* Version of this header */
> > > + grub_uint32_t res1; /* reserved */
> > > grub_uint64_t res2; /* reserved */
> > > - grub_uint64_t res3; /* reserved */
> > > - grub_uint64_t res4; /* reserved */
> > > - grub_uint32_t magic; /* Magic number, little endian,
> "RSCV" */
> > > + grub_uint64_t magic; /* magic (RISC-V specifc,
> deprecated)*/
> > > + grub_uint32_t magic2; /* Magic number 2 (to match the
> ARM64 'magic' field pos) */
> > > grub_uint32_t hdr_offset; /* Offset of PE/COFF header */
> >
> > I can agree that hdr_offset makes more sense but
> > Documentation/riscv/boot-image-header.rst names this member as res3.
> > So, I would rename hdr_offset to res3 too. Or fix
> > Documentation/riscv/boot-image-header.rst in the kernel. Or, least
> > preferred, explain in the commit message why you do not rename this
> > member and add to the comment that this member is named res3 in the
> > documentation.
> >
>
> Can we get rid of these header definitions entirely?
>
> The only GRUB code that seems to care about the fields that are not
> defined in the PE/COFF spec is grub_cmd_file(), which currently parses
> the magic field, but given that we only support EFI boot anyway, that
> code should just parse the PE machine type instead.
>
If I understand you correctly, you are suggesting to remove
the linux_arm64_kernel_header/linux_riscv_kernel_header
and just define a generic linux_arch_kernel_header which
has pe_image_header at the correct offset.
grub_cmd_file() can just compare the machine type instead of the magic
number for the IS_ARM64_LINUX case.
The other places using linux_arm64_kernel_header will just use the generic
structure to compute the section_alignment field from the PE header.
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