lkml.org 
[lkml]   [2018]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2] hpet: Fix missing '=' character in the __setup() code of hpet_mmap_enable
From
Date
On 12/20/18 5:59 PM, Greg KH wrote:
> On Thu, Dec 20, 2018 at 05:35:24PM +0530, Buland Singh wrote:
>> Commit '3d035f580699 ("drivers/char/hpet.c: allow user controlled mmap for
>> user processes")' introduced a new kernel command line parameter hpet_mmap,
>> that is required to expose the memory map of the HPET registers to
>> user-space. Unfortunately the kernel command line parameter 'hpet_mmap' is
>> broken and never takes effect due to missing '=' character in the __setup()
>> code of hpet_mmap_enable.
>>
>> Before this patch:
>>
>> dmesg output with the kernel command line parameter hpet_mmap=1
>>
>> [ 0.204152] HPET mmap disabled
>>
>> dmesg output with the kernel command line parameter hpet_mmap=0
>>
>> [ 0.204192] HPET mmap disabled
>>
>> After this patch:
>>
>> dmesg output with the kernel command line parameter hpet_mmap=1
>>
>> [ 0.203945] HPET mmap enabled
>>
>> dmesg output with the kernel command line parameter hpet_mmap=0
>>
>> [ 0.204652] HPET mmap disabled
>>
>> Fixes: 3d035f580699 ("drivers/char/hpet.c: allow user controlled mmap for user processes")
>> Signed-off-by: Buland Singh <bsingh@redhat.com>
>> ---
>> drivers/char/hpet.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
>> index 4a22b4b41aef..9bffcd37cc7b 100644
>> --- a/drivers/char/hpet.c
>> +++ b/drivers/char/hpet.c
>> @@ -377,7 +377,7 @@ static __init int hpet_mmap_enable(char *str)
>> pr_info("HPET mmap %s\n", hpet_mmap_enabled ? "enabled" : "disabled");
>> return 1;
>> }
>> -__setup("hpet_mmap", hpet_mmap_enable);
>> +__setup("hpet_mmap=", hpet_mmap_enable);

Hello Greag,

> This has _never_ worked? Since 3.13?

Yes, that's true :)

> Why not just remove the thing as it is obvious no one actually has ever used it. > That would make the code even simpler :)

Data Plane Development Kit (DPDK)[1] provides API that requires the CONFIG_HPET_MMAP
kernel configuration option to be enabled[2]. Some end users might want to use the
HPET MMAP functionality within the application.

Regards,
Buland Singh

[1] https://www.dpdk.org
[2] https://doc.dpdk.org/guides-18.08/linux_gsg/enable_func.html








\
 
 \ /
  Last update: 2018-12-20 14:43    [W:0.061 / U:44.388 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site