[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 4/5] x86: add multiboot2 protocol support for EFI platforms
On 18/01/17 14:17, Doug Goldstein wrote: > diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S > index d423fd8..ac93df0 100644 > --- a/xen/arch/x86/boot/head.S > +++ b/xen/arch/x86/boot/head.S > @@ -89,6 +89,13 @@ multiboot2_header_start: > 0, /* Number of the lines - no preference. */ \ > 0 /* Number of bits per pixel - no preference. */ > > + /* Inhibit bootloader from calling ExitBootServices(). */ /* Request that ExitBootServices() not be called. */ This tag doesn't make any guarantees. > + .code64 > + > +__efi64_start: __mb2_efi64_start: This entry point is distinct from the PE efi64 entry point in common/efi/boot.c > + cld > + > + /* VGA is not available on EFI platforms. */ > + movl $0,vga_text_buffer(%rip) > + > + /* Check for Multiboot2 bootloader. */ > + cmp $MULTIBOOT2_BOOTLOADER_MAGIC,%eax > + je .Lefi_multiboot2_proto > + > + /* Jump to not_multiboot after switching CPU to x86_32 mode. */ > + lea not_multiboot(%rip),%edi > + jmp x86_32_switch > + > +.Lefi_multiboot2_proto: > + /* Zero EFI SystemTable and EFI ImageHandle addresses. */ > + xor %esi,%esi > + xor %edi,%edi > + > + /* Skip Multiboot2 information fixed part. */ > + lea (MB2_fixed_sizeof+MULTIBOOT2_TAG_ALIGN-1)(%rbx),%ecx > + and $~(MULTIBOOT2_TAG_ALIGN-1),%ecx Are we strictly guaranteed to have the entire image, including multiboot tags, loaded below 4GB virtual even in the 64bit case? Even on non-EFI capable grub2's ? ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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