Hi, 2011/8/24 Alex Deucher <[email protected]>
> On Wed, Aug 24, 2011 at 2:14 AM, Chen Jie <[email protected]> wrote: > > Hi, > > > > 2011/8/23 Alex Deucher <[email protected]> > >> > >> > Not sure I understand it or not, but we're using the sideport way, and > >> > has a dedicated 128M DDR2 memory as VRAM. > >> > >> The default behavior of the system bios is to set up sideport memory > >> interleaved with stolen system memory. Unless your bios only enables > >> sideport you'll need to respect the stolen system memory used as vram. > >> Also, sideport memory has really limited memory bandwidth. It's a > >> powersaving feature as if you un-interleave the sideport memory, you > >> can put the display in sideport and stop memory access via the CPU. > >> For decent performance, you need to use system memory or interleaved > >> sideport and system memory. > > Got it, thanks. > > BTW, if using 128M sideport memory, will it occupy another 128M system > > memory in the default behavior? > > > > Yes. Normally the sbios reports a slightly smaller ram size to > account for the stolen memory or marks it as reserved so the OS > doesn't try and use it. We've checked the sbios setup code -- the setup logic is borrowed from coreboot, and is confirmed using the single memory channel mode. Regards, -- Chen Jie
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