Re: [Qemu-devel] [Qemu-arm] [PATCH] bcm2835_property: use cached values when querying framebuffer

[Andrew Baumann]

> From: Gerd Hoffmann [mailto:address@hidden
> Sent: Friday, 22 April 2016 09:46
>
> Alternatively we can just go for a later boot loader stage, i.e. put a u-boot 
> build
> for rpi2 to pc-bios/ (we already have one for ppc there) and run that by 
> default.
> 
> Our sdcard emulation seems to have problems though:
> 
>    U-Boot 2016.05-rc2 (Apr 22 2016 - 09:11:45 +0200)
> 
>    DRAM:  960 MiB
>    RPI 2 Model B (0xa21041)
>    MMC:   <uboot hangs here>
> 
> Recent linux kernels have trouble talking to the mmc too.

I know :( I haven't looked at the more recent kernels, but it could be the same 
issue I spent a while debugging fruitlessly on raspi1 -- it looked like Linux 
was issuing a large MMC read for N blocks, but only programming the DMA 
controller for fewer (<N*blocksize). The DMA reads completed quickly but 
eventually the kernel timed out, logged an error and reissued the whole 
operation as single-block PIO reads.

If you get a chance to diagnose this any further, I'd be curious to know what 
you find. If the same problem repros with u-boot, it's almost certainly simpler 
to debug there.

Thanks,
Andrew