於 五，2013-08-30 於 19:41 -0400，Josh Boyer 提到：
> On Fri, Aug 30, 2013 at 01:46:30PM -0700, H. Peter Anvin wrote:
> > On 08/29/2013 11:37 AM, Josh Boyer wrote:
> > >> setup_efi_pci(boot_params);
> > >> diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
> > >> index c15ddaf..d35da96 100644
> > >> --- a/arch/x86/include/uapi/asm/bootparam.h
> > >> +++ b/arch/x86/include/uapi/asm/bootparam.h
> > >> @@ -131,7 +131,8 @@ struct boot_params {
> > >> __u8 eddbuf_entries; /* 0x1e9 */
> > >> __u8 edd_mbr_sig_buf_entries; /* 0x1ea */
> > >> __u8 kbd_status; /* 0x1eb */
> > >> - __u8 _pad5[3]; /* 0x1ec */
> > >> + __u8 secure_boot; /* 0x1ec */
> > >> + __u8 _pad5[2]; /* 0x1ec */
> > >> /*
> > >> * The sentinel is set to a nonzero value (0xff) in header.S.
> > >> *
> > >
> > > You need to include the following chunk of code with this, otherwise the
> > > secure_boot variable gets cleared.
> > >
> >
> > Not really.
> >
> > There are three cases:
> >
> > 1. Boot stub only. Here we do the right thing with the bootparams.
> > 2. Boot loader bypasses the boot stub completely. Here we MUST NOT do
> > what you suggest above.
> > 3. Boot stub with a boot_params structure passed in. Here we should
> > run sanitize_boot_params() (an inline for a reason) in the boot
> > stub, before we set the secure_boot field. Once that is done, we
> > again don't need that modification.
>
> OK. If 3 works, then great. All I know is that Fedora has been
> carrying the above hunk for months and it was missing in this patch set.
> So when I went to test it, the patches didn't do anything because the
> secure_boot field was getting cleared.
>
> I'm more than happy to try option 3, and I'll poke at it next week
> unless someone beats me to it.
>
> josh
The secure_boot field cleaned by sanitize_boot_params() when using grub2
linuxefi to load efi stub kernel.
I printed the boot_params->sentinel value, confirm this value is NOT 0
when running grub2 linuxefi path, the entry point is efi_stub_entry.
On the other hand,
the sentinel value is 0 when direct run efi stub kernel in UEFI shell,
the secure_boot field can keep.
Does that mean grub2 should clean the sentinel value? or we move the get
secure_boot value to efi_init()?
Thanks a lot!
Joey Lee
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