linux-kernel - Re: i686 quirk for AMD Geode

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Message-ID: <40101cc30911081004j47f55878h1590140da8369674@mail.gmail.com>
Date:	Sun, 8 Nov 2009 19:04:35 +0100
From:	Matteo Croce <technoboy85@...il.com>
To:	Andres Salomon <dilinger@...labora.co.uk>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: i686 quirk for AMD Geode

On Sun, Nov 8, 2009 at 5:05 PM, Andres Salomon <dilinger@...labora.co.uk> wrote:
> See comment below.  BTW, how does this affect performance on LXs?
> Do you have any hard numbers for common tasks?
>
> On Sat, 7 Nov 2009 12:11:55 +0100
> Matteo Croce <technoboy85@...il.com> wrote:
> [...]
>>
>> --- a/arch/x86/kernel/Makefile        2009-11-06 15:06:52.246223989
>> +0100 +++ b/arch/x86/kernel/Makefile  2009-11-06
>> 15:07:04.294054613 +0100 @@ -89,7 +89,7 @@
>>  obj-$(CONFIG_HPET_TIMER)     += hpet.o
>>
>>  obj-$(CONFIG_K8_NB)          += k8.o
>> -obj-$(CONFIG_MGEODE_LX)              += geode_32.o mfgpt_32.o
>> +obj-$(CONFIG_MGEODE_LX)              += geode_32.o mfgpt_32.o
>> nopl_emu.o obj-$(CONFIG_DEBUG_RODATA_TEST)    += test_rodata.o
>>  obj-$(CONFIG_DEBUG_NX_TEST)  += test_nx.o
>>
>> --- a/arch/x86/kernel/cpu/amd.c       2009-11-06 15:06:52.254223805
>> +0100 +++ b/arch/x86/kernel/cpu/amd.c 2009-11-06
>> 15:07:04.294054613 +0100 @@ -138,8 +138,10 @@
>>       }
>>
>>       if (c->x86_model == 10) {
>> -             /* AMD Geode LX is model 10 */
>> -             /* placeholder for any needed mods */
>> +             /* Geode only lacks the NOPL instruction to be i686,
>> +                but we can emulate it in the exception handler
>> +                and promote it to a class 6 cpu */
>> +             boot_cpu_data.x86 = 6;
>>               return;
>>       }
>
> If you're going to update this, you also need to make sure that you're
> not breaking things that check it.  For example,
> arch/x86/include/asm/geode.h has an is_geode_lx check that expects
> boot_cpu_data.x86 to be 5.  Please be sure to update all these places
> when creating a patch like this.
>

True, but also remove the duplicate function is_geode in the NAND driver
and use the identical one defined in geode.h:

--- a/drivers/mtd/nand/cs553x_nand.c	2009-11-08 18:58:14.835043214 +0100
+++ b/drivers/mtd/nand/cs553x_nand.c	2009-11-08 19:00:07.914117831 +0100
@@ -30,6 +30,7 @@

 #include <asm/msr.h>
 #include <asm/io.h>
+#include <asm/geode.h>

 #define NR_CS553X_CONTROLLERS	4

@@ -260,23 +261,6 @@
 	return err;
 }

-static int is_geode(void)
-{
-	/* These are the CPUs which will have a CS553[56] companion chip */
-	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
-	    boot_cpu_data.x86 == 5 &&
-	    boot_cpu_data.x86_model == 10)
-		return 1; /* Geode LX */
-
-	if ((boot_cpu_data.x86_vendor == X86_VENDOR_NSC ||
-	     boot_cpu_data.x86_vendor == X86_VENDOR_CYRIX) &&
-	    boot_cpu_data.x86 == 5 &&
-	    boot_cpu_data.x86_model == 5)
-		return 1; /* Geode GX (née GX2) */
-
-	return 0;
-}
-

 #ifdef CONFIG_MTD_PARTITIONS
 static const char *part_probes[] = { "cmdlinepart", NULL };
--
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