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Re: [RFC 2/5] x86/boot: create a C bundle for 32 bit boot code and use it


  • To: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 9 Sep 2024 12:10:43 +0200
  • Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
  • Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 09 Sep 2024 10:10:52 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 04.09.2024 16:56, Frediano Ziglio wrote:
> --- a/.gitignore
> +++ b/.gitignore
> @@ -251,8 +251,7 @@ xen/System.map
>  xen/arch/x86/boot/mkelf32
>  xen/arch/x86/boot/cmdline.S
>  xen/arch/x86/boot/reloc.S
> -xen/arch/x86/boot/*.bin
> -xen/arch/x86/boot/*.lnk
> +xen/arch/x86/boot/build32.*.lds

Please retain (largely) alphabetic sorting.

> --- a/xen/arch/x86/boot/build32.lds
> +++ b/xen/arch/x86/boot/build32.lds.S
> @@ -15,22 +15,54 @@
>   * with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> -ENTRY(_start)
> +#undef ENTRY
> +
> +#ifdef FINAL
> +# define GAP 0
> +# define MULT 0
> +# define TEXT_START
> +#else
> +# define GAP 0x010200
> +# define MULT 1
> +# define TEXT_START 0x408020
> +#endif
> +# define DECLARE_IMPORT(name) name = . + (__LINE__ * MULT)
> +
> +ENTRY(dummy_start)
>  
>  SECTIONS
>  {
> -  /* Merge code and data into one section. */
> -  .text : {
> +  /* Merge code and read-only data into one section. */
> +  .text TEXT_START : {
> +        /* Silence linker warning, we are not going to use it */
> +        dummy_start = .;
> +
> +        /* Declare below any symbol name needed.
> +         * Each symbol should be on its own line.
> +         * It looks like a tedious work but we make sure the things we use.
> +         * Potentially they should be all variables. */
> +        DECLARE_IMPORT(__base_relocs_start);
> +        DECLARE_IMPORT(__base_relocs_end);
> +        . = . + GAP;
>          *(.text)
>          *(.text.*)
> -        *(.data)
> -        *(.data.*)
>          *(.rodata)
>          *(.rodata.*)
> +  }
> +
> +  /* Writeable data sections. Check empty.
> +   * We collapse all into code section and we don't want it to be writeable. 
> */
> +  .data : {
> +        *(.data)
> +        *(.data.*)
>          *(.bss)
>          *(.bss.*)
>    }
> -
> +  /DISCARD/ : {
> +       *(.comment)
> +       *(.comment.*)
> +       *(.note.*)
> +  }
>    /* Dynamic linkage sections.  Collected simply so we can check they're 
> empty. */
>    .got : {
>          *(.got)
> @@ -49,6 +81,7 @@ SECTIONS
>    }
>    .rel : {
>          *(.rel.*)
> +        *(.data.rel.*)

This looks like you're mixing up .data.rel (a data section, where some items
may require relocation) and .rel.data (the relocation section for .data). If
you want all .data.* empty, this section should be empty, too. (I also don't
think this would ever take effect, due to the earlier *(.data.*).)

Jan



 


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