casaroli opened a new pull request, #19837:
URL: https://github.com/apache/nuttx/pull/19837
## Summary
`lm3s6965-ek:qemu-protected` does not fit the part any more. The kernel
image is 132456 bytes and the user image is 130668 bytes, which is 1308 bytes
more than the 256 KiB of flash on the LM3S6965, so the kernel `.data`
initialiser runs 1384 bytes into 0x00020000, where the user image is programmed.
Nothing reported this. `memory.ld` splits the flash in two halves and bounds
the user link, but `ARCHSCRIPT` selected `ld.script`, which declares the whole
flash as one region, so nothing held the kernel to its half.
This PR makes the configuration fit and makes the boundary enforceable. It
removes what QEMU cannot use, and what other configurations of this board
already cover: MMC/SD over SPI with SSI0, because the QEMU model has no SSI;
semihosting hostfs; the GPIO interrupt ports, which no driver here uses; and
the wget example with its web client. It then links the protected kernel
against `kflash`, so a kernel that does not fit is a link error.
The result, measured with arm-none-eabi-gcc 14.2.rel1: kernel 132456 ->
124580 bytes, user image 130668 -> 125500 bytes. Each 128 KiB half now has more
than 5 KiB free.
The split itself stays at 128 KiB / 128 KiB. The ARMv7-M MPU maps the user
flash as one power-of-two region with eight sub-regions, and
`mpu_subregion_ls()` rounds the offset down to the sub-region grid, so a
boundary off that grid would give user code read and execute access to the end
of the kernel flash.
apache/nuttx-apps#3685 needs this room: it builds `testing/ostest/vfork.c`
wherever `ARCH_HAVE_VFORK` is set, and that is 328 bytes the user half does not
have today.
## Impact
Board `lm3s6965-ek` only. `qemu-protected` loses the MMC/SD driver, hostfs
and `wget`; the `nsh`, `discover` and `qemu-flat` configurations of the same
board still build the MMC/SD driver. `qemu-kostest`, the other protected
configuration of this board, is unchanged. Flat configurations still link
against `ld.script`.
## Testing
Host: macOS 15.5 on Apple Silicon, arm-none-eabi-gcc 14.2.rel1.
Built `lm3s6965-ek:qemu-protected`, `lm3s6965-ek:qemu-kostest` and
`lm3s6965-ek:qemu-flat`, each from `make distclean`.
Sizes of `qemu-protected` before and after, from `readelf -lW`:
```
before kernel 0x00000000..0x00020568 132456 B 1384 B past the 128 KiB
half
user 0x00020000..0x0003fe6c 130668 B 404 B free
after kernel 0x00000000..0x0001e8a4 124580 B 6492 B free
user 0x00020000..0x0003ea3c 125500 B 5572 B free
```
With this branch, `qemu-protected` also builds against
apache/nuttx-apps#3685, which fails against master with `region uflash
overflowed by 128 bytes`.
To show that the new kernel bound works, a build with `kflash` set to 120
KiB reports the overflow instead of silently crossing the boundary:
```
arm-none-eabi-ld: nuttx section `.text' will not fit in region `kflash'
arm-none-eabi-ld: region `kflash' overflowed by 2212 bytes
```
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