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Date:   Tue, 28 Aug 2018 17:49:56 -0700 (PDT)
Subject:     Re: [PATCH] riscv: Drop setup_initrd
In-Reply-To: <eee9cb69-6a3f-6a99-4e83-dbab3a8f5984@roeck-us.net>
CC:     schwab@linux-m68k.org, aou@eecs.berkeley.edu,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
From:   Palmer Dabbelt <palmer@sifive.com>
To:     linux@roeck-us.net
Message-ID: <mhng-f20ef153-c2be-4ba8-bd1f-9e241281b18d@palmer-si-x1c4>
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On Tue, 28 Aug 2018 17:36:28 PDT (-0700), linux@roeck-us.net wrote:
> On 08/28/2018 05:09 PM, Palmer Dabbelt wrote:
>> On Tue, 28 Aug 2018 15:12:38 PDT (-0700), linux@roeck-us.net 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@roeck-us.net wrote:
>>>> >On Tue, Aug 28, 2018 at 11:46:09PM +0200, Andreas Schwab wrote:
>>>> >>On Aug 28 2018, Guenter Roeck <linux@roeck-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@roeck-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@roeck-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 ?
>>
>> 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!