Re: [Xen-devel] [PATCH 2/2] xen/arm: support compressed kernels

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Stefano,

I'm sure you don't support all kind of compressed kernels. Can you
example in the commit message which one you are supporting?

On 12/08/15 15:47, Stefano Stabellini wrote:
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> CC: julien.grall@xxxxxxxxxx
> CC: ian.campbell@xxxxxxxxxx
> ---
>  xen/arch/arm/kernel.c           |   36 ++++++++++++++++++++++++++++++++++++
>  xen/common/Makefile             |    2 +-
>  xen/include/asm-arm/byteorder.h |    2 ++
>  3 files changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
> index f641b12..ca50cdd 100644
> --- a/xen/arch/arm/kernel.c
> +++ b/xen/arch/arm/kernel.c
> @@ -13,6 +13,8 @@
>  #include <asm/byteorder.h>
>  #include <asm/setup.h>
>  #include <xen/libfdt/libfdt.h>
> +#include <xen/decompress.h>
> +#include <xen/vmap.h>
>  
>  #include "kernel.h"
>  
> @@ -310,6 +312,38 @@ static int kernel_zimage64_probe(struct kernel_info 
> *info,
>  
>      return 0;
>  }
> +
> +static int kernel_zimage64_compressed_probe(struct kernel_info *info,
> +                                 paddr_t addr, paddr_t size)
> +{
> +    char *output, *input;
> +    unsigned char magic[2];
> +    int rc;
> +    unsigned kernel_order_in;
> +    unsigned kernel_order_out;
> +    paddr_t output_size;
> +    
> +    copy_from_paddr(magic, addr, sizeof(magic));
> +
> +    if (!((magic[0] == 0x1f) && ((magic[1] == 0x8b) || (magic[1] == 0x9e))))

Please add a comment to explain what this magic means.

Maybe you want to use gzip_check?

> +        return -EINVAL;
> +
> +    kernel_order_in = get_order_from_bytes(size);
> +    input = (char *)ioremap_cache(addr, size);

Cast not necessary. And please check that we effectively were able to
map the kernel.

> +
> +    output_size = output_length(input, size);
> +    kernel_order_out = get_order_from_bytes(output_size);
> +    output = (char *)alloc_xenheap_pages(kernel_order_out, 0);

Ditto.

> +
> +    rc = decompress(input, size, output);
> +    clean_dcache_va_range(output, output_size);
> +    iounmap(input);
> +
> +    if (rc != 0)
> +        return rc;
> +
> +    return kernel_zimage64_probe(info, virt_to_maddr(output), output_size);
> +}
>  #endif
>  
>  /*
> @@ -466,6 +500,8 @@ int kernel_probe(struct kernel_info *info)
>  #ifdef CONFIG_ARM_64
>      rc = kernel_zimage64_probe(info, start, size);
>      if (rc < 0)
> +        rc = kernel_zimage64_compressed_probe(info, start, size);
> +    if (rc < 0)
>  #endif
>          rc = kernel_uimage_probe(info, start, size);
>      if (rc < 0)

Regards,


-- 
Julien Grall

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