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Re: [PATCH v5 2/5] x86/efi: discard multiboot and PVH support for PE binary
- To: Frediano Ziglio <freddy77@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 29 Jun 2026 15:00:06 +0200
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- Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>, Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>, Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Mon, 29 Jun 2026 13:00:43 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 26.06.2026 14:36, Frediano Ziglio wrote:
> Changes since v4:
> - more clear subject;
> - removed more code/data from EFI output;
I can see that you excluded a few data items in the assembly file. But is
there actually any more code excluded? In particular the functions I
mentioned in the v4 comments are still going to remain unreachable in the
image. And addressing that doesn't look difficult at all:
tools/combine_two_binaries.py would need to have .init.text replaced just
like you do it in the assembly source.
Another thing is that with it now being crystal clear that the PVH entry
point goes away, code reachable only when it's present (first and foremost
guest/xen/pvh-boot.c) is then also unreachable. Perhaps the objcopy
involved in the .o -> .init.o conversion could be customized to rename
sections in our favor.
> @@ -135,8 +135,7 @@ multiboot2_header:
> .Lbag_alg_msg: .asciz "ERR: Xen must be loaded at a 2Mb boundary!"
> .Lno_nx_msg: .asciz "ERR: Not an NX-capable CPU!"
>
> - .section .init.data, "aw", @progbits
> - .subsection 1 /* Put data here after the page tables (in x86_64.S).
> */
> + .section .init.data.multiboot, "aw", @progbits
> .align 4
Turns out the comment must have been stale for a while.
> --- a/xen/arch/x86/xen.lds.S
> +++ b/xen/arch/x86/xen.lds.S
> @@ -57,6 +57,12 @@ SECTIONS
> __image_base__ = .;
> #else
> . = __image_base__;
> + /DISCARD/ : {
> + *(.text.header)
> + *(.init.multiboot)
> + *(.init.data.multiboot)
> + *(.init.rodata.multiboot)
Simply *(.init.*multiboot)?
Jan
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