On Wed, 9 Nov 2022 at 09:13, Atish Kumar Patra <atishp@rivosinc.com> wrote:
>
>
>
> On Tue, Nov 8, 2022 at 8:37 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>>
>> On Tue, 8 Nov 2022 at 16:59, Daniel Kiper <dkiper@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.schuchardt@canonical.com>
>> > > Signed-off-by: Atish Patra <atishp@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.
>
Exactly.
Thanks for the prompt response. I will take a stab at it and revise the series.