[U-Boot] [U-Boot, v4, 3/5] api: bootelf: go: flush cache before starting

[Tom Rini]

On Tue, Jan 31, 2017 at 12:17:06PM +0100, Emmanuel Vadot wrote:

> From: Warner Losh <imp at freebsd.org>
> 
> Some application might load some code at location that contain stale
> cache entries. Before running a elf or raw binary, flush the caches
> if they are enabled.
> 
> Reviewed-by: Tom Rini <trini at konsulko.com>
> Signed-off-by: Emmanuel Vadot <manu at bidouilliste.com>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> ---
>  api/api.c  | 5 +++++
>  cmd/boot.c | 4 ++++
>  cmd/elf.c  | 5 +++++
>  3 files changed, 14 insertions(+)
> 
> diff --git a/api/api.c b/api/api.c
> index c368511704..88b5df77c0 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;
>  
> +	if (dcache_status())
> +		flush_dcache_all();
> +	if (icache_status())
> +		invalidate_icache_all();
> +

So this runs into a problem.  Building for sandbox, or many many other
platforms gives us:
undefined reference to `dcache_status'
undefined reference to `flush_dcache_all'
undefined reference to `icache_status'
undefined reference to `invalidate_icache_all'

At the high level, we have a few problems.  We don't have a global "has
icache" and "has dcache" support CONFIG symbol.  We also have a few
instances of weak functions that end up being no-ops in these cases, but
it's not quite correct to use them in this case, possibly.  For example,
PowerPC does have dcache support and functions but no flush_dcache_all
(and only sometimes a flush_dcache() that looks like it would be
_all()), and same for icache.

-- 
Tom
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