diff --git a/src/boards/include/boards/adafruit_feather_rp2040.h b/src/boards/include/boards/adafruit_feather_rp2040.h
index 631c52d..a27f9a3 100644
--- a/src/boards/include/boards/adafruit_feather_rp2040.h
+++ b/src/boards/include/boards/adafruit_feather_rp2040.h
@@ -68,12 +68,16 @@
 #endif
 
 //------------- FLASH -------------//
+
+// Use slower generic flash access
+#define PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
-#define PICO_FLASH_SPI_CLKDIV 2
+#define PICO_FLASH_SPI_CLKDIV 4
 #endif
 
 #ifndef PICO_FLASH_SIZE_BYTES
-#define PICO_FLASH_SIZE_BYTES (4 * 1024 * 1024)
+#define PICO_FLASH_SIZE_BYTES (8 * 1024 * 1024)
 #endif
 
 // All boards have B1 RP2040
diff --git a/src/boards/include/boards/adafruit_itsybitsy_rp2040.h b/src/boards/include/boards/adafruit_itsybitsy_rp2040.h
index 55015c6..dd29d64 100644
--- a/src/boards/include/boards/adafruit_itsybitsy_rp2040.h
+++ b/src/boards/include/boards/adafruit_itsybitsy_rp2040.h
@@ -72,6 +72,9 @@
 #endif
 
 //------------- FLASH -------------//
+
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/adafruit_qtpy_rp2040.h b/src/boards/include/boards/adafruit_qtpy_rp2040.h
index cfe68ab..570fb3d 100644
--- a/src/boards/include/boards/adafruit_qtpy_rp2040.h
+++ b/src/boards/include/boards/adafruit_qtpy_rp2040.h
@@ -71,6 +71,9 @@
 #endif
 
 //------------- FLASH -------------//
+
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/pico.h b/src/boards/include/boards/pico.h
index cf45311..d681dc4 100644
--- a/src/boards/include/boards/pico.h
+++ b/src/boards/include/boards/pico.h
@@ -61,6 +61,8 @@
 
 // --- FLASH ---
 
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/pimoroni_keybow2040.h b/src/boards/include/boards/pimoroni_keybow2040.h
index eeab409..011212e 100644
--- a/src/boards/include/boards/pimoroni_keybow2040.h
+++ b/src/boards/include/boards/pimoroni_keybow2040.h
@@ -111,6 +111,8 @@
 #define KEYBOW2040_NUM_SWITCHES_PINS 16
 #endif
 
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/pimoroni_picosystem.h b/src/boards/include/boards/pimoroni_picosystem.h
index c249469..72d4789 100644
--- a/src/boards/include/boards/pimoroni_picosystem.h
+++ b/src/boards/include/boards/pimoroni_picosystem.h
@@ -124,6 +124,8 @@
 #define PICO_DEFAULT_LED_PIN_INVERTED 1
 #endif
 
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/pimoroni_tiny2040.h b/src/boards/include/boards/pimoroni_tiny2040.h
index 29194e4..6cf86b4 100644
--- a/src/boards/include/boards/pimoroni_tiny2040.h
+++ b/src/boards/include/boards/pimoroni_tiny2040.h
@@ -76,6 +76,8 @@
 #define PICO_DEFAULT_LED_PIN_INVERTED 1
 #endif
 
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/sparkfun_micromod.h b/src/boards/include/boards/sparkfun_micromod.h
index 973a9e1..d082131 100644
--- a/src/boards/include/boards/sparkfun_micromod.h
+++ b/src/boards/include/boards/sparkfun_micromod.h
@@ -47,6 +47,8 @@
 #endif
 
 // spi flash
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/sparkfun_promicro.h b/src/boards/include/boards/sparkfun_promicro.h
index d63ab41..b042d6e 100644
--- a/src/boards/include/boards/sparkfun_promicro.h
+++ b/src/boards/include/boards/sparkfun_promicro.h
@@ -46,6 +46,8 @@
 #define PICO_DEFAULT_I2C_SCL_PIN   17
 #endif
 
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/boards/include/boards/sparkfun_thingplus.h b/src/boards/include/boards/sparkfun_thingplus.h
index eac3aa4..d2a0d73 100644
--- a/src/boards/include/boards/sparkfun_thingplus.h
+++ b/src/boards/include/boards/sparkfun_thingplus.h
@@ -43,6 +43,9 @@
 #endif
 
 // spi flash
+
+#define PICO_BOOT_STAGE2_CHOOSE_W25Q080 1
+
 #ifndef PICO_FLASH_SPI_CLKDIV
 #define PICO_FLASH_SPI_CLKDIV 2
 #endif
diff --git a/src/rp2_common/boot_stage2/CMakeLists.txt b/src/rp2_common/boot_stage2/CMakeLists.txt
index 4eda064..99adf40 100644
--- a/src/rp2_common/boot_stage2/CMakeLists.txt
+++ b/src/rp2_common/boot_stage2/CMakeLists.txt
@@ -1,17 +1,34 @@
-# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2_FILE, Default stage2 file to use unless overridden by pico_set_boot_stage2 on the TARGET, type=bool, default=.../boot2_w25q080.S, group=build
-if (NOT PICO_DEFAULT_BOOT_STAGE2_FILE)
-    set(PICO_DEFAULT_BOOT_STAGE2_FILE "${CMAKE_CURRENT_LIST_DIR}/boot2_w25q080.S")
+# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2_FILE, Default stage2 file to use unless overridden by pico_set_boot_stage2 on the TARGET; this setting is useful when explicitly setting the default build from a per board CMake file, group=build
+# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2, Simpler alternative to specifying PICO_DEFAULT_BOOT_STAGE2_FILE where the file is src/boards/{PICO_DEFAULT_BOOT_STAGE2_FILE}.S, default=compile_time_choice, group=build
+if (DEFINED ENV{PICO_DEFAULT_BOOT_STAGE2_FILE})
+    set(PICO_DEFAULT_BOOT_STAGE2_FILE $ENV{PICO_DEFAULT_BOOT_STAGE2_FILE})
+    message("Using PICO_DEFAULT_BOOT_STAGE2_FILE from environment ('${PICO_DEFAULT_BOOT_STAGE2_FILE}')")
 endif()
-
 set(PICO_DEFAULT_BOOT_STAGE2_FILE "${PICO_DEFAULT_BOOT_STAGE2_FILE}" CACHE STRING "boot_stage2 source file" FORCE)
 
+set(PICO_BOOT_STAGE2_COMPILE_TIME_CHOICE_NAME compile_time_choice) # local var
+if (NOT PICO_DEFAULT_BOOT_STAGE2_FILE)
+    if (DEFINED ENV{PICO_DEFAULT_BOOT_STAGE2})
+        set(PICO_DEFAULT_BOOT_STAGE2 $ENV{PICO_DEFAULT_BOOT_STAGE2})
+        message("Using PICO_DEFAULT_BOOT_STAGE2 from environment ('${PICO_DEFAULT_BOOT_STAGE2}')")
+    endif()
+    if (NOT DEFINED PICO_DEFAULT_BOOT_STAGE2)
+        set(PICO_DEFAULT_BOOT_STAGE2 ${PICO_BOOT_STAGE2_COMPILE_TIME_CHOICE_NAME})
+    endif()
+    set(PICO_DEFAULT_BOOT_STAGE2 "${PICO_DEFAULT_BOOT_STAGE2}" CACHE STRING "boot_stage2 short name" FORCE)
+    set(PICO_DEFAULT_BOOT_STAGE2_FILE "${CMAKE_CURRENT_LIST_DIR}/${PICO_DEFAULT_BOOT_STAGE2}.S")
+endif()
+
 if (NOT EXISTS ${PICO_DEFAULT_BOOT_STAGE2_FILE})
-    message(FATAL_ERROR "Specified boot_stage2 source '${PICO_BOOT_STAGE2_FILE}' does not exist.")
+    message(FATAL_ERROR "Specified boot_stage2 source '${PICO_DEFAULT_BOOT_STAGE2_FILE}' does not exist.")
 endif()
 
 # needed by function below
 set(PICO_BOOT_STAGE2_DIR "${CMAKE_CURRENT_LIST_DIR}" CACHE INTERNAL "")
 
+add_library(boot_stage2_headers INTERFACE)
+target_include_directories(boot_stage2_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
+
 # by convention the first source file name without extension is used for the binary info name
 function(pico_define_boot_stage2 NAME SOURCES)
     add_executable(${NAME}
@@ -29,7 +46,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
     # boot2_helpers include dir
     target_include_directories(${NAME} PRIVATE ${PICO_BOOT_STAGE2_DIR}/asminclude)
 
-    target_link_libraries(${NAME} hardware_regs)
+    target_link_libraries(${NAME} hardware_regs boot_stage2_headers)
     target_link_options(${NAME} PRIVATE "LINKER:--script=${PICO_BOOT_STAGE2_DIR}/boot_stage2.ld")
     set_target_properties(${NAME} PROPERTIES LINK_DEPENDS ${PICO_BOOT_STAGE2_DIR}/boot_stage2.ld)
 
@@ -49,17 +66,22 @@ function(pico_define_boot_stage2 NAME SOURCES)
             COMMAND ${Python3_EXECUTABLE} ${PICO_BOOT_STAGE2_DIR}/pad_checksum -s 0xffffffff ${ORIGINAL_BIN} ${PADDED_CHECKSUMMED_ASM}
             )
 
-
     add_library(${NAME}_library INTERFACE)
     add_dependencies(${NAME}_library ${NAME}_padded_checksummed_asm)
     # not strictly (or indeed actually) a link library, but this avoids dependency cycle
     target_link_libraries(${NAME}_library INTERFACE ${PADDED_CHECKSUMMED_ASM})
+    target_link_libraries(${NAME}_library INTERFACE boot_stage2_headers)
 
     list(GET SOURCES 0 FIRST_SOURCE)
-    get_filename_component(BOOT2_BI_NAME ${FIRST_SOURCE} NAME_WE)
+    get_filename_component(BOOT_STAGE2_BI_NAME ${FIRST_SOURCE} NAME_WE)
 
-    target_compile_definitions(${NAME}_library INTERFACE
-            -DPICO_BOOT2_NAME="${BOOT2_BI_NAME}")
+    # we only set the PICO_BUILD_STAGE2_NAME if it isn't 'compile_time_choice'
+    if (NOT BOOT_STAGE2_BI_NAME STREQUAL PICO_BOOT_STAGE2_COMPILE_TIME_CHOICE_NAME)
+        target_compile_definitions(${NAME} INTERFACE
+                -DPICO_BUILD_BOOT_STAGE2_NAME="${BOOT_STAGE2_BI_NAME}")
+        target_compile_definitions(${NAME}_library INTERFACE
+                -DPICO_BUILD_BOOT_STAGE2_NAME="${BOOT_STAGE2_BI_NAME}")
+    endif()
 endfunction()
 
 macro(pico_set_boot_stage2 TARGET NAME)
diff --git a/src/rp2_common/boot_stage2/compile_time_choice.S b/src/rp2_common/boot_stage2/compile_time_choice.S
new file mode 100644
index 0000000..cacb9aa
--- /dev/null
+++ b/src/rp2_common/boot_stage2/compile_time_choice.S
@@ -0,0 +1,29 @@
+// ----------------------------------------------------------------------------
+// Second stage boot code
+// Copyright (c) 2019-2021 Raspberry Pi (Trading) Ltd.
+// SPDX-License-Identifier: BSD-3-Clause
+// ----------------------------------------------------------------------------
+//
+// This implementation uses the PICO_BOOT_STAGE2_CHOOSE_ preprocessor defines to pick
+// amongst a menu of known boot stage 2 implementations, allowing the board
+// configuration header to be able to specify the boot stage 2
+
+#include "boot_stage2/config.h"
+
+#ifdef PICO_BUILD_BOOT_STAGE2_NAME
+    // boot stage2 is configured by cmake, so use the name specified there
+    #error PICO_BUILD_BOOT_STAGE2_NAME should not be defined for compile_time_choice builds
+#else
+    // boot stage2 is selected by board configu header, so we have to do some work
+    #if PICO_BOOT_STAGE2_CHOOSE_IS25LP080
+        #include "boot2_is25lp080.S"
+    #elif PICO_BOOT_STAGE2_CHOOSE_W25Q080
+        #include "boot2_w28q080.S"
+    #elif PICO_BOOT_STAGE2_CHOOSE_W25X10CL
+        #include "boot2_w25x10cl.S"
+    #elif PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H
+        #include "boot2_generic_03h.S"
+    #else
+        #error unknown boot stage2 choice
+    #endif
+#endif
diff --git a/src/rp2_common/boot_stage2/include/boot_stage2/config.h b/src/rp2_common/boot_stage2/include/boot_stage2/config.h
new file mode 100644
index 0000000..f6fdb9f
--- /dev/null
+++ b/src/rp2_common/boot_stage2/include/boot_stage2/config.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef _BOOT_STAGE2_CONFIG_H_
+#define _BOOT_STAGE2_CONFIG_H_
+
+// NOTE THIS HEADER IS INCLUDED FROM ASSEMBLY
+
+// PICO_CONFIG: PICO_BUILD_BOOT_STAGE2_NAME, The name of the boot stage 2 if selected by the build, group=boot_stage2
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_IS25LP080, Select boot2_is25lp080 as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=false, group=boot_stage2
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_W25Q080, Select boot2_w28q080 as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=false, group=boot_stage2
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_W25X10CL, Select boot2_is25lp080 as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=false, group=boot_stage2
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H, Select boot2_generic_03h as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=true, group=boot_stage2
+
+#ifdef PICO_BUILD_BOOT_STAGE2_NAME
+    // boot stage2 is configured by cmake, so use the name specified there
+    #define PICO_BOOT_STAGE2_NAME PICO_BUILD_BOOT_STAGE2_NAME
+#else
+    // boot stage2 is selected by board configu header, so we have to do some work
+    // NOTE: this switch is mirrored in compile_time_choice.S
+    #if PICO_BOOT_STAGE2_CHOOSE_IS25LP080
+        #define PICO_BOOT_STAGE2_NAME "boot2_is25lp080"
+    #elif PICO_BOOT_STAGE2_CHOOSE_W25Q080
+        #define PICO_BOOT_STAGE2_NAME "boot2_w28q080"
+    #elif PICO_BOOT_STAGE2_CHOOSE_W25X10CL
+        #define PICO_BOOT_STAGE2_NAME "boot2_w25x10cl"
+    #elif PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H || !defined(PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H)
+        #undef PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H
+        #define PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H 1
+        #define PICO_BOOT_STAGE2_NAME "boot2_generic_03h"
+    #else
+        #error no bootstage2 is defined by PICO_BOOT_STAGE2_CHOOSE_ macro
+    #endif
+#endif
+#endif
\ No newline at end of file
diff --git a/src/rp2_common/pico_standard_link/CMakeLists.txt b/src/rp2_common/pico_standard_link/CMakeLists.txt
index 489594c..c58096d 100644
--- a/src/rp2_common/pico_standard_link/CMakeLists.txt
+++ b/src/rp2_common/pico_standard_link/CMakeLists.txt
@@ -14,7 +14,7 @@ if (NOT TARGET pico_standard_link)
         target_link_options(pico_standard_link INTERFACE "LINKER:-nostdlib")
     endif ()
 
-    target_link_libraries(pico_standard_link INTERFACE hardware_regs pico_bootrom pico_binary_info pico_cxx_options)
+    target_link_libraries(pico_standard_link INTERFACE hardware_regs boot_stage2_headers pico_bootrom pico_binary_info pico_cxx_options)
 
     function(pico_add_link_depend TARGET dependency)
         get_target_property(target_type ${TARGET} TYPE)
diff --git a/src/rp2_common/pico_standard_link/binary_info.c b/src/rp2_common/pico_standard_link/binary_info.c
index ba5dad8..bde2027 100644
--- a/src/rp2_common/pico_standard_link/binary_info.c
+++ b/src/rp2_common/pico_standard_link/binary_info.c
@@ -6,6 +6,7 @@
 
 #if !PICO_NO_BINARY_INFO && !PICO_NO_PROGRAM_INFO
 #include "pico/binary_info.h"
+#include "boot_stage2/config.h"
 
 // Note we put at most 4 pieces of binary info in the reset section because that's how much spare space we had
 // (picked the most common ones)... if there is a link failure because of .reset section overflow then move
@@ -66,9 +67,9 @@ bi_decl(bi_program_url(PICO_PROGRAM_URL))
 #endif
 #endif
 
-#if !PICO_NO_BI_BOOT2_NAME
-#ifdef PICO_BOOT2_NAME
-bi_decl(bi_string(BINARY_INFO_TAG_RASPBERRY_PI, BINARY_INFO_ID_RP_BOOT2_NAME, PICO_BOOT2_NAME))
+#if !PICO_NO_BI_BOOT_STAGE2_NAME
+#ifdef PICO_BOOT_STAGE2_NAME
+bi_decl(bi_string(BINARY_INFO_TAG_RASPBERRY_PI, BINARY_INFO_ID_RP_BOOT2_NAME, PICO_BOOT_STAGE2_NAME))
 #endif
 #endif