On 23/10/2019 22:21, Segher Boessenkool wrote: > On Wed, Oct 23, 2019 at 12:36:35PM +1100, Oliver O'Halloran wrote: >> When booting under OF the zImage expects the initrd address and size to be >> passed to it using registers r3 and r4. SLOF (guest firmware used by QEMU) >> currently doesn't do this so the zImage is not aware of the initrd >> location. This can result in initrd corruption either though the zImage >> extracting the vmlinux over the initrd, or by the vmlinux overwriting the >> initrd when relocating itself. >> >> QEMU does put the linux,initrd-start and linux,initrd-end properties into >> the devicetree to vmlinux to find the initrd. We can work around the SLOF >> bug by also looking those properties in the zImage. > > This is not a bug. What boot protocol requires passing the initrd start > and size in GPR3, GPR4? So far I was unable to identify it... > The CHRP binding (what SLOF implements) requires passing two zeroes here. > And ePAPR requires passing the address of a device tree and a zero, plus > something in GPR6 to allow distinguishing what it does. > > As Alexey says, initramfs works just fine, so please use that? initrd was > deprecated when this code was written already. I did not say about anything working fine :) In my case I was using a new QEMU which does full FDT on client-arch-support and that thing would put the original linux,initrd-start/end to the FDT even though the initrd was unpacked and the properties were changes in SLOF. With that fixed, this is an alternative fix for SLOF but I am not pushing it out as I have no idea about the bindings and this also breaks "vmlinux". diff --git a/slof/fs/client.fs b/slof/fs/client.fs index 8a7f6ac4326d..138177e4c2a3 100644 --- a/slof/fs/client.fs +++ b/slof/fs/client.fs @@ -45,6 +45,17 @@ VARIABLE client-callback \ Address of client's callback function >r ciregs >r7 ! ciregs >r6 ! client-entry-point @ ciregs >r5 ! \ Initialise client-stack-pointer cistack ciregs >r1 ! + + s" linux,initrd-end" get-chosen IF decode-int -rot 2drop ELSE 0 THEN + s" linux,initrd-start" get-chosen IF decode-int -rot 2drop ELSE 0 THEN + 2dup - dup IF + ciregs >r4 ! + ciregs >r3 ! + drop + ELSE + 3drop + THEN + -- Alexey
