Re: [Xen-devel] debian stretch dom0 + xen 4.9 fails to boot

[Juergen Gross <jgross@xxxxxxxx>]

On 08/06/17 14:42, Paul Durrant wrote:
> For those following this...
> 
> By poking characters at the screen and bisecting where they stopped, I have 
> narrowed the problem to the code in edd.S. I can successfully boot by setting 
> opt_edd=off on the Xen cmd line and I can also boot with the following patch 
> applied:
> 
> diff --git a/xen/arch/x86/boot/edd.S b/xen/arch/x86/boot/edd.S
> index 73371f98b5..5409f1d9a1 100644
> --- a/xen/arch/x86/boot/edd.S
> +++ b/xen/arch/x86/boot/edd.S
> @@ -148,5 +148,6 @@ GLOBAL(boot_mbr_signature_nr)
>          .byte   0
>  GLOBAL(boot_mbr_signature)
>          .fill   EDD_MBR_SIG_MAX*8,1,0
> +       .align  4096
>  GLOBAL(boot_edd_info)
> -        .fill   512,1,0                         # big enough for a disc 
> sector
> +        .fill   4096,1,0                         # big enough for a disc 
> sector
> 
> (based on a hunch that the BIOS defaults to a 4K sector for my NVMe drive)
> 
> I need to investigate some more but I do wonder whether the EDD info should 
> be read first to determine the appropriate size of memory buffer to use when 
> issuing the read of the MBR. Hardcoding a 4k reservation seems like the wrong 
> thing to do, even if it is sufficient for this BIOS
Thanks for rehabilitation of my patch. :-)


Juergen

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