linux-kernel - Re: [PATCH] riscv: Drop setup

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Message-ID: <20180828221238.GA6605@roeck-us.net>
Date:   Tue, 28 Aug 2018 15:12:38 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Palmer Dabbelt <palmer@...ive.com>
Cc:     schwab@...ux-m68k.org, aou@...s.berkeley.edu,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: Drop setup_initrd

On Tue, Aug 28, 2018 at 03:03:00PM -0700, Palmer Dabbelt wrote:
> On Tue, 28 Aug 2018 14:59:59 PDT (-0700), linux@...ck-us.net wrote:
> >On Tue, Aug 28, 2018 at 11:46:09PM +0200, Andreas Schwab wrote:
> >>On Aug 28 2018, Guenter Roeck <linux@...ck-us.net> 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@...ck-us.net 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@...ck-us.net>
> >>>> >---
> >>>> > 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 ?

Thanks,
Guenter