On Sun, Oct 30, 2011 at 09:39:37PM +0100, Marc Dietrich wrote: > On Friday 28 October 2011 09:49:49 Stephen Warren wrote: > > I also see a bunch of code to set up the memory > > information from DT e.g. setup_machine_fdt()'s call to: > > > > of_scan_flat_dt(early_init_dt_scan_memory, NULL); > > > > ... but I assume that happens before the ATAGs are processed, and the > > buggy ATAGs end up overriding the information in the DT file. And further, > > I assume that specifying "mem=" on the command-line overrides that, thus > > solving the problem. > > > > It'd be awesome if you could validate this; the simplest way is probably > > to: > > > > a) Remove mem= from the command-line > > I tested several variations. Without DT, the fixup can compensate a missing > mem entry in the kernel command line, but with a mem= from the kernel command > line, a fixup is not needed. > > With DT, the command line specified from nvflash is ignored and the one from > DT comes into the game. If it is also missing there, system detects 512 MB > (which is physical right, but we cannot reserve memory for the gpu). The fixup > is indeed ignored in this case. The /memreserve/ fields are supposed to allow you to do this. > > > b) Modify arch/arm/kernel/setup.c:parse_tag_mem32() to do nothing; > > comment out the call to arm_add_memory() > > I leave this out because the bootloader does not send memory info in the > ATAGS. > > > c) Test booting, and check what RAM size the kernel thinks you have. > > see above. RAM detection works, but it's not what we want ... > > > If that works, then ATAGs are the problem. We probably need to modify the > > core ARM code not to use memory ATAGs when there is a DT? > > > > I'm mainly pushing on this because adding "mem=" to the command-line in > > the DT file isn't a great solution; when people start using bootloaders > > that rewrite the DT to include the user-specified command-line, then every > > user is going to have to start specifying "mem=" in their command-lines. > > Well, I see two options for our case: > > a) use the mem=448M@0 in the DT so the gpu can get its memory > b) upstream the chromeos changes to reserve gpu memory "on the fly" from > the autodetected 512M (as it should be IMHO). b) is the ideal. a) is absolutely wrong. /memreserve/ should fix the gpu memory problem when not passing a mem= parameter. If /memreserve/ isn't working, then I'd like to know why. g. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
