Re: [PATCH] riscv: Drop setup_initrd

[Palmer Dabbelt]

On Tue, 28 Aug 2018 17:36:28 PDT (-0700), linux@xxxxxxxxxxxx wrote:
> On 08/28/2018 05:09 PM, Palmer Dabbelt wrote:
> > 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)
> > > > >>>> >-{
> > > > >>>> >-ÂÂÂ extern char __initramfs_start[];
> > > > >>>> >-ÂÂÂ extern unsigned long __initramfs_size;
> > > > >>>> >-ÂÂÂ unsigned long size;
> > > > >>>> >-
> > > > >>>> >-ÂÂÂ if (__initramfs_size > 0) {
> > > > >>>> >-ÂÂÂÂÂÂÂ initrd_start = (unsigned long)(&__initramfs_start);
> > > > >>>> >-ÂÂÂÂÂÂÂ initrd_end = initrd_start + __initramfs_size;
> > > > >>>> >-ÂÂÂ }
> > > > >>>
> > > > >>> 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
> > > > >>>
> > > > >>> -ÂÂÂ if (__initramfs_size > 0) {
> > > > >>> +ÂÂÂ 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
> > > >
> > > > ÂÂ diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > > > ÂÂ index db20dc630e7e..aee603123030 100644
> > > > ÂÂ --- a/arch/riscv/kernel/setup.c
> > > > ÂÂ +++ b/arch/riscv/kernel/setup.c
> > > > ÂÂ @@ -85,15 +85,8 @@ atomic_t hart_lottery;
> > > > ÂÂÂ #ifdef CONFIG_BLK_DEV_INITRD
> > > > ÂÂÂ static void __init setup_initrd(void)
> > > > ÂÂÂ {
> > > > ÂÂ -ÂÂÂ extern char __initramfs_start[];
> > > > ÂÂ -ÂÂÂ extern unsigned long __initramfs_size;
> > > > ÂÂÂÂÂÂÂ unsigned long size;
> > > > ÂÂ -ÂÂÂ if (__initramfs_size > 0) {
> > > > ÂÂ -ÂÂÂÂÂÂÂ initrd_start = (unsigned long)(&__initramfs_start);
> > > > ÂÂ -ÂÂÂÂÂÂÂ initrd_end = initrd_start + __initramfs_size;
> > > > ÂÂ -ÂÂÂ }
> > > > ÂÂ -
> > > > ÂÂÂÂÂÂÂ if (initrd_start >= initrd_end) {
> > > > ÂÂÂÂÂÂÂÂÂÂÂ printk(KERN_INFO "initrd not found or empty");
> > > > ÂÂÂÂÂÂÂÂÂÂÂ 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).
>
> Done.
>
> There is no need to override initrd_start and initrd_end; populate_rootfs()
> uses __initramfs_start and __initramfs_size directly when loading a built-in
> initramfs. initrd_start and initrd_end, on the other side, are for an external
> initrd, loaded separately (and initialized in __early_init_dt_declare_initrd()).

OK, that makes sense.  I dropped your patch onto for-next, assuming nothing's 
gone wrong it should go in next week.  It boots a Fedora rootfs for me.

Thanks!