2009-12-09 06:27:45

by Cong Wang

[permalink] [raw]
Subject: [Patch] i386: remove 'usedac' kernel parameter

It is scheduled to be removed.

Signed-off-by: WANG Cong <[email protected]>
Cc: Glauber Costa <[email protected]>
Cc: Ingo Molnar <[email protected]>

---
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 591e944..8c895f6 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -291,13 +291,6 @@ Who: Michael Buesch <[email protected]>

---------------------------

-What: usedac i386 kernel parameter
-When: 2.6.27
-Why: replaced by allowdac and no dac combination
-Who: Glauber Costa <[email protected]>
-
----------------------------
-
What: print_fn_descriptor_symbol()
When: October 2009
Why: The %pF vsprintf format provides the same functionality in a
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index afcc58b..2f76c7b 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -210,10 +210,6 @@ static __init int iommu_setup(char *p)
forbid_dac = 0;
if (!strncmp(p, "nodac", 5))
forbid_dac = 1;
- if (!strncmp(p, "usedac", 6)) {
- forbid_dac = -1;
- return 1;
- }
#ifdef CONFIG_SWIOTLB
if (!strncmp(p, "soft", 4))
swiotlb = 1;


2009-12-09 10:08:35

by FUJITA Tomonori

[permalink] [raw]
Subject: Re: [Patch] i386: remove 'usedac' kernel parameter

On Wed, 9 Dec 2009 01:25:48 -0500
Amerigo Wang <[email protected]> wrote:

> It is scheduled to be removed.
>
> Signed-off-by: WANG Cong <[email protected]>
> Cc: Glauber Costa <[email protected]>
> Cc: Ingo Molnar <[email protected]>
>
> ---
> diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
> index 591e944..8c895f6 100644
> --- a/Documentation/feature-removal-schedule.txt
> +++ b/Documentation/feature-removal-schedule.txt
> @@ -291,13 +291,6 @@ Who: Michael Buesch <[email protected]>
>
> ---------------------------
>
> -What: usedac i386 kernel parameter
> -When: 2.6.27
> -Why: replaced by allowdac and no dac combination
> -Who: Glauber Costa <[email protected]>
> -
> ----------------------------
> -

I'm not sure about the above description, I'm not against removing
this option though.

IIUC, the usedac option enables us to stop via_no_dac() setting
forbid_dac to 1. That is, someone who uses VIA bridges can use DAC
with this option even if some of VIA bridges seem to be broken about
DAC. I can't see how we can do the same thing with "allowdac" and
"nodac" combination.

2009-12-14 07:47:11

by Cong Wang

[permalink] [raw]
Subject: Re: [Patch] i386: remove 'usedac' kernel parameter

FUJITA Tomonori wrote:
> On Wed, 9 Dec 2009 01:25:48 -0500
> Amerigo Wang <[email protected]> wrote:
>
>> It is scheduled to be removed.
>>
>> Signed-off-by: WANG Cong <[email protected]>
>> Cc: Glauber Costa <[email protected]>
>> Cc: Ingo Molnar <[email protected]>
>>
>> ---
>> diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
>> index 591e944..8c895f6 100644
>> --- a/Documentation/feature-removal-schedule.txt
>> +++ b/Documentation/feature-removal-schedule.txt
>> @@ -291,13 +291,6 @@ Who: Michael Buesch <[email protected]>
>>
>> ---------------------------
>>
>> -What: usedac i386 kernel parameter
>> -When: 2.6.27
>> -Why: replaced by allowdac and no dac combination
>> -Who: Glauber Costa <[email protected]>
>> -
>> ----------------------------
>> -
>
> I'm not sure about the above description, I'm not against removing
> this option though.
>
> IIUC, the usedac option enables us to stop via_no_dac() setting
> forbid_dac to 1. That is, someone who uses VIA bridges can use DAC
> with this option even if some of VIA bridges seem to be broken about
> DAC. I can't see how we can do the same thing with "allowdac" and
> "nodac" combination.


Hmm, yes, right, I missed this point.

Thanks!