Re: [PATCH] riscv: Drop setup_initrd

[Palmer Dabbelt]

On Tue, 28 Aug 2018 15:12:38 PDT (-0700), linux@xxxxxxxxxxxx wrote:
> On Tue, Aug 28, 2018 at 03:03:00PM -0700, Palmer Dabbelt wrote:
> > On Tue, 28 Aug 2018 14:59:59 PDT (-0700), linux@xxxxxxxxxxxx wrote:
> > >On Tue, Aug 28, 2018 at 11:46:09PM +0200, Andreas Schwab wrote:
> > >>On Aug 28 2018, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > >>
> > >>> On Tue, Aug 28, 2018 at 01:10:20PM -0700, Palmer Dabbelt wrote:
> > >>>> On Thu, 09 Aug 2018 21:11:40 PDT (-0700), linux@xxxxxxxxxxxx wrote:
> > >>>> >setup_initrd() does not appear to serve a practical purpose other than
> > >>>> >preventing qemu boots with "-initrd" parameter, so let's drop it.
> > >>>> >
> > >>>> >Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > >>>> >---
> > >>>> > arch/riscv/kernel/setup.c | 39 ---------------------------------------
> > >>>> > 1 file changed, 39 deletions(-)
> > >>>> >
> > >>>> >diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > >>>> >index 2e56af3281f8..579f58a42974 100644
> > >>>> >--- a/arch/riscv/kernel/setup.c
> > >>>> >+++ b/arch/riscv/kernel/setup.c
> > >>>> >@@ -82,41 +82,6 @@ EXPORT_SYMBOL(empty_zero_page);
> > >>>> > /* The lucky hart to first increment this variable will boot the other cores */
> > >>>> > atomic_t hart_lottery;
> > >>>> >
> > >>>> >-#ifdef CONFIG_BLK_DEV_INITRD
> > >>>> >-static void __init setup_initrd(void)
> > >>>> >-{
> > >>>> >-	extern char __initramfs_start[];
> > >>>> >-	extern unsigned long __initramfs_size;
> > >>>> >-	unsigned long size;
> > >>>> >-
> > >>>> >-	if (__initramfs_size > 0) {
> > >>>> >-		initrd_start = (unsigned long)(&__initramfs_start);
> > >>>> >-		initrd_end = initrd_start + __initramfs_size;
> > >>>> >-	}
> > >>>
> > >>> The underlying problem is probably that __initramfs_size == 512 even
> > >>> if there is no embedded initrd. Result is that initrd_start and initrd_end
> > >>> are always overwritten, even if provided and even if there is no embedded
> > >>> initrd. Result is that initrd_start and initrd_end are always overwritten,
> > >>> and -initrd from the qemu command line is always ignored.
> > >>>
> > >>> A less invasive fix than mine would be
> > >>>
> > >>> -	if (__initramfs_size > 0) {
> > >>> +	if (__initramfs_size > 0 && !initrd_start) {
> > >>>
> > >>> Any chance you can test that with your setup ?
> > >>
> > >>You should just delete the last four lines above.  They serve no purpose.
> > >>
> > >
> > >You mean the entire if() statement plus the variable declarations ?
> > >
> > >That works for me, for both embedded initrd and initrd specified with
> > >-initrd option, but we still need someone to test if it works for
> > >Palmer's use case, ie with vmlinux (and possibly initrd) embedded in
> > >bbl.
> >
> > This still boots my Fedora images
> >
> >    diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> >    index db20dc630e7e..aee603123030 100644
> >    --- a/arch/riscv/kernel/setup.c
> >    +++ b/arch/riscv/kernel/setup.c
> >    @@ -85,15 +85,8 @@ atomic_t hart_lottery;
> >     #ifdef CONFIG_BLK_DEV_INITRD
> >     static void __init setup_initrd(void)
> >     {
> >    -	extern char __initramfs_start[];
> >    -	extern unsigned long __initramfs_size;
> >     	unsigned long size;
> >    -	if (__initramfs_size > 0) {
> >    -		initrd_start = (unsigned long)(&__initramfs_start);
> >    -		initrd_end = initrd_start + __initramfs_size;
> >    -	}
> >    -
> >     	if (initrd_start >= initrd_end) {
> >     		printk(KERN_INFO "initrd not found or empty");
> >     		goto disable;
> >
> > but I have not tried an integrated initramfs.
>
> I tested the above both with external initrd and with integrated
> initramfs; both work for me.
>
> Should I resend my patch, using the above, or do you want to create
> a patch yourself ?

You should send one, then it'll go through my regular pre-PR testing flow to 
make sure it works on my end.  I just never trust these inline patches to be 
exact, even if it's unlikely there's any confusion on a patch this simple (at 
least, mechanically simple -- I'm afraid I still don't understand why the logic 
is incorrect).