Re: [PATCH] x86/trampoline: fallback to fixed trampoline address if no e820 map is provided

[Yinghai]

On Dec 23, 2010, at 1:57 AM, Florian Fainelli <ffainelli@xxxxxxxxxx> wrote:

> On Tuesday 14 December 2010 22:19:39 Florian Fainelli wrote:
>> From: Florian Fainelli <ffainelli@xxxxxxxxxx>
>> 
>> Since 893f38d1 (x86: Use find_e820() instead of hard coded trampoline
>> address), the trampoline base address should be provided by the BIOS as an
>> e820 area. Some minimalistic BIOSes (like CEFDK on CE4100) may not provide
>> any e820 area, still we should fallback to a fixed trampoline base address
>> for SMP to work correctly.

No e820 memmap ?

Not sure how does it work

Do you have boot log with debug ?

Also recent kernel is using memblock already for finding free area.

Thanks



>> 
>> Cc: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>
>> Cc: sodaville@xxxxxxxxxxxxx
>> Cc: Ingo Molnar <mingo@xxxxxxx>
>> Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
>> Signed-off-by: Florian Fainelli <ffainelli@xxxxxxxxxx>
> 
> Ingo, Yinghai, anything wrong with that patch? Thank you.
> 
>> ---
>> diff --git a/arch/x86/include/asm/trampoline.h
>> b/arch/x86/include/asm/trampoline.h index f4500fb..908b395 100644
>> --- a/arch/x86/include/asm/trampoline.h
>> +++ b/arch/x86/include/asm/trampoline.h
>> @@ -16,6 +16,7 @@ extern unsigned long initial_code;
>> extern unsigned long initial_gs;
>> 
>> #define TRAMPOLINE_SIZE roundup(trampoline_end - trampoline_data,
>> PAGE_SIZE) +#define TRAMPOLINE_BASE 0x6000
>> 
>> extern unsigned long setup_trampoline(void);
>> extern void __init reserve_trampoline_memory(void);
>> diff --git a/arch/x86/kernel/trampoline.c b/arch/x86/kernel/trampoline.c
>> index f1488a3..d025aae 100644
>> --- a/arch/x86/kernel/trampoline.c
>> +++ b/arch/x86/kernel/trampoline.c
>> @@ -21,8 +21,11 @@ void __init reserve_trampoline_memory(void)
>> 
>>    /* Has to be in very low memory so we can execute real-mode AP code. */
>>    mem = find_e820_area(0, 1<<20, TRAMPOLINE_SIZE, PAGE_SIZE);
>> -    if (mem == -1L)
>> -        panic("Cannot allocate trampoline\n");
>> +    if (mem == -1L) {
>> +        printk(KERN_INFO "BIOS did not provide e820 area for trampoline"
>> +                " ,using static trampoline address\n");
>> +        mem = TRAMPOLINE_BASE;
>> +    }
>> 
>>    trampoline_base = __va(mem);
>>    reserve_early(mem, mem + TRAMPOLINE_SIZE, "TRAMPOLINE");
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/