[U-Boot] [PATCH v2 3/4] api: FreeBSD: flush cache before starting loader/kernel

[Emmanuel Vadot]

On Tue, 17 Jan 2017 21:58:31 +0100
Alexander Graf <agraf at suse.de> wrote:

> 
> 
> On 17/01/2017 21:45, Emmanuel Vadot wrote:
> > On Tue, 17 Jan 2017 21:13:51 +0100
> > Alexander Graf <agraf at suse.de> wrote:
> >
> >>
> >>
> >> On 17/01/2017 16:50, Emmanuel Vadot wrote:
> >>> From: Warner Losh <imp at freebsd.org>
> >>>
> >>> FreeBSD loader(8) just loaded code to some random location that may
> >>> contain stale icache entries.
> >>> FreeBSD Kernel needs the icache and dcache flushed.
> >>> Before running either one of them, flush the icache and dcache.
> >>>
> >>> Signed-off-by: Emmanuel Vadot <manu at bidouilliste.com>
> >>
> >> Is there any downside to doing the flush always? I would prefer to not
> >> conditionalize it on CONFIG_FREEBSD.
> >
> >  I don't think there is any downside.
> >
> >>> ---
> >>>  api/api.c  | 5 +++++
> >>>  cmd/boot.c | 5 +++++
> >>>  cmd/elf.c  | 8 +++++++-
> >>>  3 files changed, 17 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/api/api.c b/api/api.c
> >>> index 8a1433af78..cc25deca09 100644
> >>> --- a/api/api.c
> >>> +++ b/api/api.c
> >>> @@ -290,6 +290,11 @@ static int API_dev_close(va_list ap)
> >>>  	if (!err)
> >>>  		di->state = DEV_STA_CLOSED;
> >>>
> >>> +#ifdef CONFIG_FREEBSD
> >>> +	flush_dcache_all();
> >>> +	invalidate_icache_all();
> >>> +#endif
> >>> +
> >>>  	return err;
> >>>  }
> >>>
> >>> diff --git a/cmd/boot.c b/cmd/boot.c
> >>> index 72f2cf362d..a1a91fbf0a 100644
> >>> --- a/cmd/boot.c
> >>> +++ b/cmd/boot.c
> >>> @@ -19,6 +19,11 @@ __attribute__((weak))
> >>>  unsigned long do_go_exec(ulong (*entry)(int, char * const []), int argc,
> >>>  				 char * const argv[])
> >>>  {
> >>> +#ifdef CONFIG_FREEBSD
> >>> +	flush_dcache_all();
> >>> +	invalidate_icache_all();
> >>> +#endif
> >>> +
> >>>  	return entry (argc, argv);
> >>>  }
> >>>
> >>> diff --git a/cmd/elf.c b/cmd/elf.c
> >>> index 5190cc6c0f..b2827fa042 100644
> >>> --- a/cmd/elf.c
> >>> +++ b/cmd/elf.c
> >>> @@ -109,6 +109,7 @@ static unsigned long do_bootelf_exec(ulong (*entry)(int, char * const[]),
> >>>  {
> >>>  	unsigned long ret;
> >>>
> >>> +#ifndef CONFIG_FREEBSD
> >>>  	/*
> >>>  	 * QNX images require the data cache is disabled.
> >>>  	 * Data cache is already flushed, so just turn it off.
> >>> @@ -116,15 +117,20 @@ static unsigned long do_bootelf_exec(ulong (*entry)(int, char * const[]),
> >>>  	int dcache = dcache_status();
> >>>  	if (dcache)
> >>>  		dcache_disable();
> >>
> >> Can FreeBSD boot with dcache disabled? Is there some way we can
> >> determine what payload we have from the elf header?
> >>
> >>
> >> Alex
> >
> >  FreeBSD can boot with dcache disabled (our loader and kernel can)
> >  I'm not sure I get your other question, sorry.
> 
> Your patch #ifdefs out the dcache_disable() if CONFIG_FREEBSD is set. So 
> if you can boot just fine with dcache disabled, you can remove this hunk 
> altogether FWIW.

 Loading the kernel from our loader is much faster with dcache enabled
(1 sec instead of 5/7 sec).
 I guess we can always flush the cache and only disable it for QNX,
I'll check if there is a CONFIG_QNX or something like that.

> All the other changes in this file are mere cache flushes - and they 
> shouldn't hurt any u-boot api user and thus could be done unconditionally.

 True, I can remove the #ifdefs on CONFIG_FREEBSD here.

> 
> Alex


-- 
Emmanuel Vadot <manu at bidouilliste.com> <manu at freebsd.org>