[linuxsh-dev] Re: [linux-sh:02749] [PATCH] Ensure flush_page_to_ram does

[Stuart M. <stu...@st...>]

Alex

Abe-san found a similar problem when using my TLB miss handling patches.
When using PIO there is no cache synchronisation in the generic IDE code,
while NFS has an explicit call to flush_dcache_page.

The solution we tried which has worked so far is based on the Sparc code,
which redefines the IO functions to include a cache synchronisation call.
The patch is attached. 

Abe-san has seen some problems when using DMA, which I've not been able
to reproduce here, but PIO appears fine now.

Stuart


On Tue, 20 May 2003 11:07:42 +0100 ker...@be... wrote:

> Hi,
> 
> The reason we where seeing issues with executing from hard disk was due
> to cache behaviour. We fixed it by applying this patch:
> 
> --- ../../../linuxsh-2.4/include/asm-sh/pgtable.h       2003-04-10
> 17:19:24.000000000 +0100
> +++ pgtable.h   2003-05-20 10:56:26.000000000 +0100
> @@ -62,7 +62,7 @@
>  extern void flush_icache_range(unsigned long start, unsigned long end);
>  extern void flush_cache_sigtramp(unsigned long addr);
>   
> -#define flush_page_to_ram(page)                        do { } while (0)
> +#define flush_page_to_ram(page)                       
> flush_dcache_page(page)
>  #define flush_icache_page(vma,pg)              do { } while (0)
>   
>  /* Initialization of P3 area for copy_user_page */
> 
> To ensure the data loaded from disk (with PIO) was properly cached in
> the processor. We think this issue was avoided with booting from NFS
> because of different cache behaviour when DMA is involved.
> 
> flush_page_to_ram is a deprecated function but thats something that
> would need to be sorted out in the main tree. Comments?
> 
> -- 
> Alex, homepage: http://www.bennee.com/~alex/
> 
> There are only two kinds of men -- the dead and the deadly.
> 		-- Helen Rowland
>