[Xen-devel] Re: xen-kernel and EDD

[Keir Fraser <keir@xxxxxxx>]

On 24/08/2011 08:50, "Lin-Bao Zhang" <2004.zhang@xxxxxxxxx> wrote:

> what a pity !
> 
> it seems that our modification :
> 1. Change BOOT_TRAMPOLINE to 0x7c000
> 2. In xen/arch/x86/boot/head.S, change the line 'mov $0x98000,%esp' to
> 'mov $0x80000,%esp'.
> has make things worse ,

Ah yes, the BOOT_TRAMPOLINE address is hardcoded into the trampoline_gdt
array in trampoline.S. You need to replace the definitions at
xen/arch/x86/boot/trampoline.S:trampoline_gdt with the following:

trampoline_gdt:
        /* 0x0000: unused */
        .quad   0x0000000000000000
        /* 0x0008: ring 0 code, 32-bit mode */
        .quad   0x00cf9a000000ffff
        /* 0x0010: ring 0 code, 64-bit mode */
        .quad   0x00af9a000000ffff
        /* 0x0018: ring 0 data */
        .quad   0x00cf92000000ffff
        /* 0x0020: real-mode code @ BOOT_TRAMPOLINE */
        .long   0x0000ffff | ((BOOT_TRAMPOLINE & 0x00ffff) << 16)
        .long   0x00009a00 | ((BOOT_TRAMPOLINE & 0xff0000) >> 16)
        /* 0x0028: real-mode data @ BOOT_TRAMPOLINE */
        .long   0x0000ffff | ((BOOT_TRAMPOLINE & 0x00ffff) << 16)
        .long   0x00009200 | ((BOOT_TRAMPOLINE & 0xff0000) >> 16)

That should fix things. This is from xen-unstable:16147 by the way.

 -- Keir

> after this picture
> :https://picasaweb.google.com/lh/photo/_XQU3pCYJ9bSL4UgvBhFJem26SCOd2WkElE8x5u
> AaOk?feat=directlink
>  system no response again ,and then reset .
> I no longer can see
> - 1706-Smart Array Controller EBDA Memory Corrupted
>   INT 13h BIOS Cannot Coninue - Sytem Halted
> 
> Again !
>  I doubt , maybe xen-kernel has corrupted before ³get_edd² due to our
> modification.
> this is indeed a gloomy day indeed!
> 
> Now , it seems that things get more complicated :
> I think there are two factors will affect :
>  - Ensure Stack can't overlap HP's P410i EBDA area
>  - Ensure Brocade card's option rom code can't overwrite P410i EBDA.
> 
> I also did another experiment :for speaking exactly, I use
> :5.7s_xen-kernel(0x98000 stack and 0x90000 for BOOT_TRAMPOLINE) and
> modified-xen-kernel(0x80000 STACK and 0x7c000 for BOOT_TRAMPOLINE) .
> 
> a)enable Brocade card(two ports) , but disable its option rom code) .
> https://picasaweb.google.com/lh/photo/lVIqQjo2PESpX1JIzpEu0oIUdNTBh7One3tGCKQ3
> AHk?feat=directlink
> 
>  * 5.7s_xen-kernel can boot successfully(edd=on)
>       from this point ,it seems that 0x98000 didn't overlap P410i EBDA. I just
> disabled Brocade option rom.
>  *  MODIFIED_xen-kernel can't boot successfully ,it also just print
> https://picasaweb.google.com/lh/photo/_XQU3pCYJ9bSL4UgvBhFJem26SCOd2WkElE8x5uA
> aOk?feat=directlink
>  no "INT13
> BIOS Cannot Continue - System Halted".
>  and no response, and then system reset.
> 
> -Bob



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