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Re: [PATCH 1/2] efi: Call FreePages only if needed
- To: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Fri, 8 Aug 2025 12:20:33 +0200
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- Cc: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>, Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Fri, 08 Aug 2025 10:20:49 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 08.08.2025 12:14, Ross Lagerwall wrote:
> On Wed, Aug 6, 2025 at 7:16 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> On 05.08.2025 18:32, Ross Lagerwall wrote:
>>> If the config file is builtin, cfg.addr will be zero but Xen
>>> unconditionally calls FreePages() on the address.
>>>
>>> Xen may also call FreePages() with a zero address if blexit() is called
>>> after this point since cfg.need_to_free is not set to false.
>>>
>>> The UEFI specification does not say whether calling FreePages() with a
>>> zero address is allowed so let's be cautious and use cfg.need_to_free
>>> properly.
>>
>> Well, no, this paragraph makes no sense. Of course this is allowed, but
>> not as no-op behavior (like free(NULL) would be), but to free memory
>> starting at 0.
>
> Fair enough. This paragraph could simply be dropped then.
>
>>
>>> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
>>
>> This pretty clearly wants a Fixes: tag, or maybe it even needs to be two.
>> I've checked the original code in 4.2, and things were consistent there,
>> afaics. So breakage was introduced perhaps in one or two of the many
>> re-works.
>>
>
> Fixes: 8a71d50ed40b ("efi: Enable booting unified
> hypervisor/kernel/initrd images")
> Fixes: 04be2c3a0678 ("efi/boot.c: add file.need_to_free")
>
> Do you want an updated patch or can these tweaks be done while committing?
If the maintainers have no other requests that require a v2, I'm sure this
can be done while committing.
Jan
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