Re: [PATCH] n_tty: use kmalloc() instead of vmalloc() to avoid crash on armada-xp

[Stas Sergeev <stsp@list.ru>]

12.03.2015 15:47, Thomas Petazzoni пишет:
> Dear Stas Sergeev,
>
>
>> The only problem I now have is the lack of 256Mb of
>> ram.
>>
>> [    0.000000] MEMBLOCK
>> configuration:                                         
>> [    0.000000]  memory size = 0x1f0000000 reserved size =
>> 0x70d6e3             
>> [    0.000000]  memory.cnt  =
>> 0x2                                              
>> [    0.000000]  memory[0x0]     [0x00000000000000-0x000000efffffff],
>> 0xf0000000
>> bytes flags:
>> 0x0                                                               
>> [    0.000000]  memory[0x1]     [0x00000100000000-0x000001ffffffff],
>> 0x100000000
>>  bytes flags: 0x0 
>>
>> There is a 8Gb in a single dimm.
>> Do you have any idea why 0xf0000000-0xffffffff range is missing?
>> I suspect this is something with uboot too.
> No, this is expected. Your physical address space is shared between RAM
> and I/O devices. So the space 0xf0000000 -> 0xffffffff in the physical
> address space is where all the registers for your SoC and PCIe devices
Yeah, I realize that, but I was hoping that some work-around
exists. For example, move entire dimm above 4G? Is this really
impossible? Or maybe move overlapping region above 8G...

> will be located. You are therefore indeed losing 256 MB of RAM, but
> there's nothing that can be done about this.
OK, that's sad.
Thanks for info!