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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org, Daniel Kiper <dkiper@net-space.pl>,
	Glenn Washburn <development@efficientek.com>
Subject: Re: [PATCH] efi/libstub: Disable PCI DMA before grabbing the EFI memory map
Date: Tue, 27 Jun 2023 09:17:06 +0100	[thread overview]
Message-ID: <20230627081706.GA20814@srcf.ucam.org> (raw)
In-Reply-To: <CAMj1kXF7g92VqnjWwbp0Y9hKXfMc2iZSmvtT2B6ZEHQ3c478bA@mail.gmail.com>

On Tue, Jun 27, 2023 at 10:14:16AM +0200, Ard Biesheuvel wrote:

> Not quite. It should only fail the first time if the memory map
> changed since the last call to GetMemoryMap(), and normally, this will
> only happen if some kind of asynchronous event was triggered after
> GetMemoryMap() but before ExitBootServices(). (This is why calling
> ExitBootServices() at most twice should always suffice: the first call
> disables the timer interrupt, so the second time around, no events
> will fire in the mean time)

Can't driver shutdown code also end up altering it? I've certainly had 
extremely deterministic requirements to call it twice, which doesn't 
line up terribly well with it just being down to async events.

  reply	other threads:[~2023-06-27  8:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-27  7:41 [PATCH] efi/libstub: Disable PCI DMA before grabbing the EFI memory map Ard Biesheuvel
2023-06-27  8:00 ` Matthew Garrett
2023-06-27  8:14   ` Ard Biesheuvel
2023-06-27  8:17     ` Matthew Garrett [this message]
2023-06-27  8:32       ` Ard Biesheuvel
2023-06-27  8:37         ` Matthew Garrett
2023-06-27  8:47           ` Ard Biesheuvel

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