| Message ID | 20191113062939.63861-1-aik@ozlabs.ru |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2] client: Load initramdisk location | expand |
On 13/11/2019 17:29, Alexey Kardashevskiy wrote: > For ages both vmlinux and zImage accepted the initramdisk location > in r3/r4 [1] [2]. If r3==r4==0, vmlinux looks at the device tree for > /chosen/linux,initrd-{start|end} but zImage does not so the QEMU user > can only pass vmlinux via -kernel if -initrd is passed as well. > > This initializes r3/r4 to point to the initramdisk location when present. > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/kernel/prom_init.c?h=v5.3#n3230 > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/boot/of.c?h=v5.3#n89 > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Pushed out. > --- > Changes: > v2: > * improved readability > --- > slof/fs/client.fs | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/slof/fs/client.fs b/slof/fs/client.fs > index 8a7f6ac4326d..db7a1925792c 100644 > --- a/slof/fs/client.fs > +++ b/slof/fs/client.fs > @@ -45,6 +45,14 @@ 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 nip nip ELSE 0 THEN > + s" linux,initrd-start" get-chosen IF decode-int nip nip ELSE 0 THEN > + ( end start ) > + tuck - ( start len ) > + ciregs >r4 ! > + ciregs >r3 ! > + > \ jump-client maps to call_client in slof/entry.S > \ When jump-client returns, R3 holds the address of a NUL-terminated string > \ that holds the client interface word the client wants to call, R4 holds >
diff --git a/slof/fs/client.fs b/slof/fs/client.fs index 8a7f6ac4326d..db7a1925792c 100644 --- a/slof/fs/client.fs +++ b/slof/fs/client.fs @@ -45,6 +45,14 @@ 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 nip nip ELSE 0 THEN + s" linux,initrd-start" get-chosen IF decode-int nip nip ELSE 0 THEN + ( end start ) + tuck - ( start len ) + ciregs >r4 ! + ciregs >r3 ! + \ jump-client maps to call_client in slof/entry.S \ When jump-client returns, R3 holds the address of a NUL-terminated string \ that holds the client interface word the client wants to call, R4 holds
For ages both vmlinux and zImage accepted the initramdisk location in r3/r4 [1] [2]. If r3==r4==0, vmlinux looks at the device tree for /chosen/linux,initrd-{start|end} but zImage does not so the QEMU user can only pass vmlinux via -kernel if -initrd is passed as well. This initializes r3/r4 to point to the initramdisk location when present. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/kernel/prom_init.c?h=v5.3#n3230 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/boot/of.c?h=v5.3#n89 Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- Changes: v2: * improved readability --- slof/fs/client.fs | 8 ++++++++ 1 file changed, 8 insertions(+)