Re: RPI4 usb, external ssd

[email protected] (Greg Troxel) writes:

>total memory = 2970 MB
>avail memory = 2862 MB
>xhci0 at acpi0 (XHC0, PNP0D10-0): mem 0x600000000-0x600000fff irq 175
>xhci0: 64-bit DMA
>xhci0: xHCI version 1.0

This is how it looks without UEFI, the 3GB restriction is handled
by the PCI driver (here on an early RPI4 with 4GB):

total memory = 3947 MB
avail memory = 3804 MB
...
bcm2838pcie0 at simplebus0: Broadcom PCIE Host Controller
bcm2838pcie0: Using 3GB DMA subregion
bcm2838pcie0: MMIO (32-bit): 0xf8000000+0x4000000@0x600000000
RootBridge Revision 304
pci0 at bcm2838pcie0 bus 0
pci0: memory space enabled
ppb0 at pci0 dev 0 function 0: vendor 14e4 product 2711 (rev. 0x10)
ppb0: PCI Express capability version 2 <Root Port of PCI-E Root Complex> x1 @ 5.
0GT/s
pci1 at ppb0 bus 1
pci1: memory space enabled
xhci0 at pci1 dev 0 function 0: vendor 1106 product 3483 (rev. 0x01)
xhci0: 64-bit DMA
xhci0: interrupting at GIC irq 175
xhci0: xHCI version 1.0

N.B. the 3GB limit might have been lifted on later revisions of the SoC,
but I haven't seen any details.