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Re: [PATCH] disk/efi: skip iPXE dummy block devices
From: |
Michael Chang |
Subject: |
Re: [PATCH] disk/efi: skip iPXE dummy block devices |
Date: |
Tue, 14 Mar 2017 11:03:07 +0800 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Mon, Mar 13, 2017 at 06:45:02AM +0300, Andrei Borzenkov wrote:
> iPXE adds Simple File System Protocol to loaded image handle, as side
> effect it also adds Block IO protocol (according to comments, to work
> around some bugs in EDK2). GRUB assumes that every device with Block IO
> is disk and skips network initialization entirely. But iPXE Block IO
> implementation is just a stub which always fails for every operation
> so cannot be used. Attempt to detect and skip such devices.
>
> We are using media ID which iPXE sets to "iPXE" and block IO size in
> hope that no real device would announce 1B block ...
>
> Closes: 50518
>
> @Vladimir, @Daniel - this is probably 2.02 material. We cannot use
> any device that advertises block size less than 512B anyway, so it
> should not cause regression for disk boot.
>
> It is my fault, I have seen it earlier but was busy with another problem
> so just worked around it to continue testing.
>
> ---
> grub-core/disk/efi/efidisk.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/grub-core/disk/efi/efidisk.c b/grub-core/disk/efi/efidisk.c
> index 3b79f7b..47a4e99 100644
> --- a/grub-core/disk/efi/efidisk.c
> +++ b/grub-core/disk/efi/efidisk.c
> @@ -80,6 +80,15 @@ make_devices (void)
> /* This should not happen... Why? */
> continue;
>
> + /* iPXE adds stub Block IO protocol to loaded image device handle. It
> is
> + completely non-functional and simply returns an error for every
> method.
> + So attempt to detect and skip it. Magic number is literal "iPXE" and
> + check block size as well */
> + /* FIXME: shoud we close it? We do not do it elsewhere */
> + if (bio->media && bio->media->media_id == 0x69505845U &&
It seems that BE to LE conversion is required here as it tests for 'EXPi' on LE
systems.
Thanks,
Michael
> + bio->media->block_size == 1)
> + continue;
> +
> d = grub_malloc (sizeof (*d));
> if (! d)
> {
> --
> tg: (bcf3c55..) bug/50518 (depends on: master)
>
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