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Re: [PATCH] Mini-OS: x86: zero out .bss segment at boot


  • To: Jürgen Groß <jgross@xxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Wed, 7 Feb 2024 11:46:42 +0100
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  • Cc: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>, minios-devel@xxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, wl@xxxxxxx
  • Delivery-date: Wed, 07 Feb 2024 10:46:52 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 07.02.2024 11:42, Jürgen Groß wrote:
> On 07.02.24 11:38, Samuel Thibault wrote:
>> Juergen Gross, le mer. 07 févr. 2024 11:31:38 +0100, a ecrit:
>>> The .bss segment should be zeroed at very early boot.
>>
>> Is that not done by the elf loader of Xen?
> 
> It might be done by Xen tools today, but I'm quite sure it is not part
> of the ABI. The hypervisor doesn't clear .bss when loading a domain (e.g.
> dom0).

libelf's elf_memcpy() looks to say otherwise.


> I stumbled over it while implementing kexec in Mini-OS. For that I need
> it for sure.

Hmm, yes, if the protocol there doesn't guarantee zeroing. But then you
probably want to give this as the reason for the change?

Jan



 


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