Re: [PATCH v3 4/4] tests/tcg/aarch64: Extend MTE gdbstub tests to system mode

[Richard Henderson <richard.henderson@linaro.org>]

On 8/28/24 04:01, Gustavo Romero wrote:
>   SECTIONS
>   {
> -    /* virt machine, RAM starts at 1gb */
> +    /* Skip first 1 GiB on virt machine: RAM starts at 1 GiB. */
>       . = (1 << 30);

Better is to use

MEMORY {
   RAM (rwx) : ORIGIN = 1 << 30, LENGTH = 16M
}

(or whatever minimum length seems reasonable).

Since there is only one memory region, it will be used by default and no further markup is 
required.

> +    /* Align text to first 2 MiB. */
> +    . = ALIGN(0 * 2M);

This is pointless, of course: ALIGN(0) does nothing.

> @@ -19,12 +21,12 @@ SECTIONS
>           *(.bss)
>       }
>       /*
> -     * Align the MTE page to the next 2mb boundary (i.e., the third 2mb chunk
> -     * starting from 1gb) by setting the address for symbol 'mte_page', which is
> -     * used in boot.S to setup the PTE and in the mte.S test as the address that
> -     * the MTE instructions operate on.
> +     * Align the MTE page to the next 2 MiB boundary (i.e., the third 2 MiB
> +     * chunk starting from 1 GiB) by setting the address for symbol 'mte_page',
> +     * which is used in boot.S to setup the PTE and in the mte.S test as the
> +     * address that the MTE instructions operate on.
>        */
> -    mte_page = ALIGN(1 << 22);
> +    mte_page = ALIGN(2 * 2M);

This does not do what you think it does.
It aligns to the next 4M boundary, not the next 2M boundary.


r~