Re: [Xen-devel] [PATCH v3] xen: Allow a default compiled-in command line using Kconfig

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.03.17 at 14:48, <julien.grall@xxxxxxx> wrote:
> On 03/07/2017 12:52 PM, Jan Beulich wrote:
>>>>> On 07.03.17 at 12:21, <blackskygg@xxxxxxxxx> wrote:
>>> 2017-03-07 17:36 GMT+08:00 Jan Beulich <JBeulich@xxxxxxxx>:
>>>>>>> On 07.03.17 at 09:34, <blackskygg@xxxxxxxxx> wrote:
>>>>> +static inline char* __init extract_dom0_options(char *cmdline)
>>>>> +{
>>>>> +    char *kextra;
>>>>> +
>>>>> +    if ( (kextra = strstr(cmdline, " -- ")) != NULL )
>>>>> +    {
>>>>> +        *kextra = '\0';
>>>>> +        kextra += 3;
>>>>> +        while ( kextra[1] == ' ' ) kextra++;
>>>>
>>>> The body of the while() wants to go on its own line.
>>>>
>>>> And then - why is this Dom0 option handling done only on x86?
>>>>
>>>
>>> As you might have noticed, there isn't any code dealing with the dom0 
>>> options
>>> in arch/arm/setup.c, and the arm version of construct_dom0() doesn't take 
>>> any
>>> command line options as its parameter,
>>> so I have the reason to believe that this feature is not available
>>> under the arm architecture.
>>
>> Looks like an omission to me - Julien, Stefano?
> 
> DOM0 and Xen command line are passed separately through either Device 
> Tree or for UEFI xen configuration file (see -cfg=...).
> 
> So I am not sure to understand what would be the benefits to handle DOM0 
> parameters after -- on Xen command line.

So you have no case of a boot loader which allows you to type in
extra options on just a single line? On x86 the feature had originally
been added because old grub didn't have a separate line for Dom0
options in its graphical menu. Nowadays the functionality is handy
namely when starting xen.efi from the EFI shell (where again you
obviously only have a single command line), but quite likely this may
also be of use with grub's chain loading model (which I simply don't
use very often, so I'm not finally sure on that one).

Jan


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