Hi, Huacai
On 09/05/2022 03:24 PM, Huacai Chen wrote:
Hi, Ard and Youling,
On Mon, Sep 5, 2022 at 3:02 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
On Mon, 5 Sept 2022 at 05:51, Huacai Chen <chenhuacai@xxxxxxxxxx> wrote:
Hi, Ard,
On Mon, Sep 5, 2022 at 5:59 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
On Sun, 4 Sept 2022 at 15:24, Huacai Chen <chenhuacai@xxxxxxxxxx> wrote:
Hi, Ard,
On Thu, Sep 1, 2022 at 6:40 PM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote:
Hi, Ard,
On Sat, Aug 27, 2022 at 3:14 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
On Sat, 27 Aug 2022 at 06:41, Xi Ruoyao <xry111@xxxxxxxxxxx> wrote:
Tested V3 with the magic number check manually removed in my GRUB build.
The system boots successfully. I've not tested Arnd's zBoot patch yet.
I am Ard not Arnd :-)
Please use this branch when testing the EFI decompressor:
https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/?h=efi-decompressor-v4
The root cause of LoongArch zboot boot failure has been found, it is a
binutils bug, latest toolchain with the below patch can solve the
problem.
diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 5b44901b9e0..fafdc7c7458 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -2341,9 +2341,10 @@ loongarch_elf_relocate_section (bfd
*output_bfd, struct bfd_link_info *info,
case R_LARCH_SOP_PUSH_PLT_PCREL:
unresolved_reloc = false;
- if (resolved_to_const)
+ if (!is_undefweak && resolved_to_const)
{
relocation += rel->r_addend;
+ relocation -= pc;
break;
}
else if (is_undefweak)
Huacai
Now the patch is submitted here:
https://sourceware.org/pipermail/binutils/2022-September/122713.html
Great. Given the severity of this bug, I imagine that building the
LoongArch kernel will require a version of binutils that carries this
fix.
Therefore, i will revert back to the original approach for accessing
uncompressed_size, using an extern declaration with an __aligned(1)
attribute.
And I have some other questions about kexec: kexec should jump to the
elf entry or the pe entry? I think is the elf entry, because if we
jump to the pe entry, then SVAM will be executed twice (but it should
be executed only once). However, how can we jump to the elf entry if
we use zboot? Maybe it is kexec-tool's responsibility to decompress
the zboot kernel image?
Yes, very good point. Kexec kernels cannot boot via the EFI entry
point, as the boot services will already be shutdown. So the kexec
kernel needs to boot via the same entrypoint in the core kernel that
the EFI stub calls when it hands over.
For the EFI zboot image in particular, we will need to teach kexec how
to decompress them. The zboot image has a header that
a) describes it as a EFI linux zimg
b) describes the start and end offset of the compressed payload
c) describes which compression algorithm was used.
This means that any non-EFI loader (including kexec) should be able to
extract the inner PE/COFF image and decompress it. For arm64 and
RISC-V, this is sufficient as the EFI and raw images are the same. For
LoongArch, I suppose it means we need a way to enter the core kernel
directly via the entrypoint that the EFI stub uses when handing over
(and pass the original DT argument so the kexec kernel has access to
the EFI and ACPI firmware tables)
OK, then is this implementation [1] acceptable? I remember that you
said the MS-DOS header shouldn't contain other information, so I guess
this is unacceptable?
No, this looks reasonable to me. I objected to using magic numbers in
the 'pure PE' view of the image, as it does not make sense for a pure
PE loader such as GRUB to rely on such metadata.
In this case (like on arm64), we are dealing with something else: we
need to identify the image to the kernel itself, and here, using the
unused space in the MS-DOS header is fine.
[1] https://lore.kernel.org/loongarch/c4dbb14a-5580-1e47-3d15-5d2079e88404@xxxxxxxxxxx/T/#mb8c1dc44f7fa2d3ef638877f0cd3f958f0be96ad
OK, then there is no big problem here. And I found that arm64/riscv
don't need the kernel entry point in the header. I don't know why, but
I think it implies that a unified layout across architectures is
unnecessary, and I prefer to put the kernel entry point before
effective kernel size. :)
The kernel entry point is added because LoongArch has not implemented
purgatory in kexec-tools, so I want to get it from the head through a
simpler method, similar to the elf image operation.
Youling.
Huacai
Huacai
