← Back to team overview

ac100 team mailing list archive

Re: Tegra Binary Driver and Memory Carve-Out


On Fri, 27 Sep 2013 11:03:13 +0200, Marc Dietrich <marvin24@xxxxxx> wrote:
Am Freitag, 27. September 2013, 08:50:05 schrieb Gordan Bobic:
 On Wed, 25 Sep 2013 13:47:25 +0400, Andrey Danin

 <andrey.danin@xxxxxxxxx> wrote:
> On Wed, 2013-09-25 at 10:10 +0100, Gordan Bobic wrote:
>> The default Tegra memory carve-out is 64MB. But my
>>  Xorg.0.log says:
>>  (--) TEGRA(0): VideoRAM: 32768 kByte
>>  tegra_drv.so does not understand a "VideoRAM" option.
>>  I tried experimenting with reclaiming some memory from
>>  the top 64MB with the Tegra driver loaded, and Xorg
>>  crashes instantly if this is attempted (62MB memory
>>  reclaim works fine with fbdev_drv.so).
>>  Does anybody know what is eating those other 32MB of
>>  RAM if the tegra_drv.so is only using 32MB? I tried
>>  playign with the nvmem parameter but that seems to
>>  get ignored on everything but the most ancient of AC100
>>  kernels.

There is also some space needed for lp0 support code.

I tried various permutations of leaving an extra 4MB
untouched at 448MB, and around 480MB, being unsure
whether the binary driver might try to use the memory from
top or bottom, but it didn't really work out.

With a fbdev, I can safely use
mem=448MB@0M mem=62M@450M
to gain an extra 62MB of RAM. The difference is very
very noticeable if you are running on slow-storage and
swapping, although it's not all that noticeable on my
heavily modified AC100 with a 2000 IOPS internal USB
SSD (Supertalent RC8).

 Not that I think it's relevant since it is a fairly low

 level tegra memory usage map question, but here goes:
> What is your kernel version? from my gitorious tree (includes 1280x720
 screen patches and overclocking patches.

> What cmdline do you use?

 $ dmesg | grep "command line"
 Kernel command line: vmalloc=320M video=tegrafb console=tty0 ro
 usbcore.old_scheme_first=1 elevator=deadline zcache quiet

> What is tegra driver version ?

 The latest available for soft-float distributions,
 from Alpha 15-something release. Xorg ABI v10 (ABI v7
 until yesterday).

You should really try a newer kernel, but you may run into problems with the
kernel graphics abi becuase you require softfloat. I think 3.0 is the
lastest kernel which may work with soft-float drivers.

I thought kernel and userspace don't need to follow the same ABI. I have
certainly run hard-float kernels with soft-float userspace and vice
versa. Samsung Chromebook, for example, has a soft-float kernel (armv7l)
but hard-float userspace.

Either way, I don't see what the kernel has to do with clawing back memory
from GPU usage.


Follow ups