Re: [build bug] lguest build failure: drivers/lguest/x86/switcher_32.S:(.text+0x3815f8): undefined reference to `LGUEST_PAGES_regs_trapnum'

Sergio Luis
2008-02-17T14:06:18Z

Thomas Gleixner wrote:
> On Mon, 4 Feb 2008, Rusty Russell wrote:
>
>> On Saturday 02 February 2008 04:05:51 Ingo Molnar wrote:
>>> looks similar to the previous one so i guess my quick fix attempt was a
>>> bit too quick. Will turn lguest off again. And i'm willing to test
>>> patches as well :)
>> Hi Ingo,
>>
>> OK, this problem was caused by asm-offsets.c only having the offsets when
>> lguest *guest* support was set, not lguest host (host support used to imply
>> guest support, so now they're separate these bugs come out).
>>
>> Can you throw this patch into your tree for testing?
>>
>> Thanks,
>> Rusty.
>
> Applied. Thanks,
>
> tglx
>

It doesn't fix the problem totally. If we select
Virtualization->Linux hypervisor example code (CONFIG_LGUEST)
as a module, we will get the same build errors, since the related
offsets won't be generated in include/asm-x86/asm-offset.h
>From arch/x86/kernel/asm_offsets_32.c
[...]
#ifdef CONFIG_LGUEST
BLANK();
OFFSET(LGUEST_PAGES_host_gdt_desc, lguest_pages, state.host_gdt_desc);
OFFSET(LGUEST_PAGES_host_idt_desc, lguest_pages, state.host_idt_desc);
OFFSET(LGUEST_PAGES_host_cr3, lguest_pages, state.host_cr3);
OFFSET(LGUEST_PAGES_host_sp, lguest_pages, state.host_sp);
OFFSET(LGUEST_PAGES_guest_gdt_desc, lguest_pages,state.guest_gdt_desc);
OFFSET(LGUEST_PAGES_guest_idt_desc, lguest_pages,state.guest_idt_desc);
OFFSET(LGUEST_PAGES_guest_gdt, lguest_pages, state.guest_gdt);
OFFSET(LGUEST_PAGES_regs_trapnum, lguest_pages, regs.trapnum);
OFFSET(LGUEST_PAGES_regs_errcode, lguest_pages, regs.errcode);
OFFSET(LGUEST_PAGES_regs, lguest_pages, regs);
#endif
[...]

-sergio

>> Lguest guest support and host support are separate config options: they used
>> to be tied together. Sort out which parts of asm-offsets are needed for Guest
>> and Host.
>>
>> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
>>
>> diff -r 7d5a5c7a4b95 arch/x86/kernel/asm-offsets_32.c
>> --- a/arch/x86/kernel/asm-offsets_32.c Sat Feb 02 23:13:05 2008 +1100
>> +++ b/arch/x86/kernel/asm-offsets_32.c Sun Feb 03 10:13:19 2008 +1100
>> @@ -20,10 +20,8 @@
>>
>> #include <xen/interface/xen.h>
>>
>> -#ifdef CONFIG_LGUEST_GUEST
>> #include <linux/lguest.h>
>> #include "../../../drivers/lguest/lg.h"
>> -#endif
>>
>> #define DEFINE(sym, val) \
>> asm volatile("\n->" #sym " %0 " #val : : "i" (val))
>> @@ -134,6 +132,10 @@ void foo(void)
>> BLANK();
>> OFFSET(LGUEST_DATA_irq_enabled, lguest_data, irq_enabled);
>> OFFSET(LGUEST_DATA_pgdir, lguest_data, pgdir);
>> +#endif
>> +
>> +#ifdef CONFIG_LGUEST
>> + BLANK();
>> OFFSET(LGUEST_PAGES_host_gdt_desc, lguest_pages, state.host_gdt_desc);
>> OFFSET(LGUEST_PAGES_host_idt_desc, lguest_pages, state.host_idt_desc);
>> OFFSET(LGUEST_PAGES_host_cr3, lguest_pages, state.host_cr3);
>>
> --
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