picolibc: Allow default memory layout values to be configured

These values are used when constructing the default linker scripts
used with picolibc. Setting reasonable defaults allows simple test
applications to be compiled without additional configuration.

Signed-off-by: Keith Packard <keithp@keithp.com>

config/libc/picolibc.in

@@ -123,3 +123,43 @@ config LIBC_PICOLIBC_EXTRA_CONFIG_ARRAY
     default ""
     help
       Extra flags to pass to meson when configuring picolibc.
+
+config LIBC_PICOLIBC_DEFAULT_FLASH_ADDR
+    string
+    prompt "Default flash address for picolibc.ld"
+    default "0x10000000"
+    help
+      Sets the default base adddress for the read-only portion of the
+      application when linked using the default picolibc link
+      script. Can be overridden on the linker command line using
+      -Wl,--defsym=__flash=<value>
+
+config LIBC_PICOLIBC_DEFAULT_FLASH_SIZE
+    string
+    prompt "Default flash size for picolibc.ld"
+    default "0x00010000"
+    help
+      Sets the default size for the read-only portion of the
+      application when linked using the default picolibc link script.
+      Can be overridden on the linker command line using
+      -Wl,--defsym=__flash_size=<value>
+
+config LIBC_PICOLIBC_DEFAULT_RAM_ADDR
+    string
+    prompt "Default ram address for picolibc.ld"
+    default "0x20000000"
+    help
+      Sets the default base adddress for the read-write portion of the
+      application when linked using the default picolibc link
+      script. Can be overridden on the linker command line using
+      -Wl,--defsym=__ram=<value>
+
+config LIBC_PICOLIBC_DEFAULT_RAM_SIZE
+    string
+    prompt "Default ram size for picolibc.ld"
+    default "0x00008000"
+    help
+      Sets the default size for the read-write portion of the
+      application when linked using the default picolibc link script.
+      Can be overridden on the linker command line using
+      -Wl,--defsym=__ram_size=<value>

scripts/build/companion_libs/340-picolibc.sh

@@ -82,6 +82,10 @@ endian = '${CT_ARCH_ENDIAN}'
 c_args = [ ${meson_cflags} '-nostdlib', '-fno-common', '-ftls-model=local-exec' ]
 needs_exe_wrapper = true
 skip_sanity_check = true
+default_flash_addr = '${CT_LIBC_PICOLIBC_DEFAULT_FLASH_ADDR}'
+default_flash_size = '${CT_LIBC_PICOLIBC_DEFAULT_FLASH_SIZE}'
+default_ram_addr = '${CT_LIBC_PICOLIBC_DEFAULT_RAM_ADDR}'
+default_ram_size = '${CT_LIBC_PICOLIBC_DEFAULT_RAM_SIZE}'
 EOF
 
     local picolibc_sysroot_dir