CompactFlash (CF) dma_timer_expiry dma status 0x21

Assumption: you are using a CF as an HD

and you get dma_timer_expiry: dma status == 0x21 on the booting log or Grub is blocked on loading stage 2

FIRST solution

In the BIOS set the ide containing the CF to PIO mode 3 or mode 4 disabling UDMA

SECOND solution

add the parameter "ide=nodma" to the kernel line of grub