[U-Boot] [PATCH v8 12/30] sandbox: Try to start the RAM buffer at a particular address

[Alexander Graf]

> Am 22.06.2018 um 21:28 schrieb Simon Glass <sjg at chromium.org>:
> 
> Hi Alex,
> 
>> On 22 June 2018 at 06:10, Alexander Graf <agraf at suse.de> wrote:
>>> On 06/21/2018 09:45 PM, Simon Glass wrote:
>>> 
>>> Hi Alex,
>>> 
>>>> On 21 June 2018 at 03:58, Alexander Graf <agraf at suse.de> wrote:
>>>> 
>>>>> On 06/21/2018 04:02 AM, Simon Glass wrote:
>>>>> 
>>>>> Hi Alex,
>>>>> 
>>>>>> On 20 June 2018 at 02:51, Alexander Graf <agraf at suse.de> wrote:
>>>>>> 
>>>>>>> On 06/20/2018 12:02 AM, Simon Glass wrote:
>>>>>>> 
>>>>>>> Hi Alex,
>>>>>>> 
>>>>>>>> On 18 June 2018 at 08:45, Alexander Graf <agraf at suse.de> wrote:
>>>>>>>> 
>>>>>>>>> On 06/18/2018 04:08 PM, Simon Glass wrote:
>>>>>>>>> 
>>>>>>>>> Use a starting address of 256MB which should be available. This
>>>>>>>>> helps
>>>>>>>>> to
>>>>>>>>> make sandbox RAM buffers pointers more recognisable.
>>>>>>>>> 
>>>>>>>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>>>>>>> 
>>>>>>>> 
>>>>>>>> Nak, this has a non-0 chance of failing, in case something else is
>>>>>>>> already
>>>>>>>> mapped at that address. You don't want to have your CI blow up 1% of
>>>>>>>> the
>>>>>>>> time due to this.
>>>>>>> 
>>>>>>> It's just a hint though. Everything will still work if it doesn't get
>>>>>>> this exact address.
>>>>>> 
>>>>>> 
>>>>>> I don't see what it buys us then.
>>>>> 
>>>>> These are my thoughts:
>>>>> 
>>>>> 1. We get an address before 4GB which is needed for grub (so far as I
>>>>> can
>>>>> tell)
>>>> 
>>>> 
>>>> We only need that in the memory map which you want virtual (U-Boot
>>>> address
>>>> space) anyway. So there's no need to also have the Linux address be <4GB.
>>> 
>>> Grub cannot work without <4GB, right? I don't mind either way, but I
>>> think it that if we are picking an address, picking a smaller one is
>>> better.
>> 
>> 
>> Only if you expose host pointers as memory addresses. We don't anymore, and
>> grub doesn't care whether a pointer is >4G.
> 
> We have to provide grub with pointers to memory with sandbox. These
> will be pointers into the sandbox RAM buffer. If this buffer is >=4GB
> then grub will not work, from my testing.

It works just fine for me?


Alex