[PATCH] board: rpi: Update memory layout for Aarch64
Tom Rini
trini at konsulko.com
Tue Jul 16 19:21:13 CEST 2024
On Tue, Jul 16, 2024 at 02:16:02PM -0300, Walter Lozano wrote:
> ARM and Aarch64 have different restrictions and trying to accommodate
> larger kernels like the ones used in distros can be challenging. For this
> reason, separate the layout and rearrange the map for Aarch64 to support
> kernels larger than 36 MB.
>
> Signed-off-by: Walter Lozano <walter.lozano at collabora.com>
> ---
>
> board/raspberrypi/rpi/rpi.env | 25 ++++++++++++++++++-------
> 1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/board/raspberrypi/rpi/rpi.env b/board/raspberrypi/rpi/rpi.env
> index 30228285edd..37c7f6a920e 100644
> --- a/board/raspberrypi/rpi/rpi.env
> +++ b/board/raspberrypi/rpi/rpi.env
> @@ -42,13 +42,19 @@ dfu_alt_info+=zImage fat 0 1
> * For Aarch64, the kernel image is uncompressed and must be loaded at
> * text_offset bytes (specified in the header of the Image) into a 2MB
> * boundary. The 'booti' command relocates the image if necessary. Linux uses
> - * a default text_offset of 0x80000. In summary, loading at 0x80000
> - * satisfies all these constraints and reserving memory up to 0x02400000
> - * permits fairly large (roughly 36M) kernels.
> + * a default text_offset of 0x80000. However, loading it at 0x80000
> + * will allow to reserve only up to 0x02400000 which permits medium size
> + * kernels (roughly 36M). This is good enough for customized kernels but
> + * not for distros which by default enable drivers for many different
> + * boards. Under these circumstances, using 0x00200000 provides room for
> + * larger kernels.
> *
> * scriptaddr and pxefile_addr_r can be pretty much anywhere that doesn't
> * conflict with something else. Reserving 1M for each of them at
> - * 0x02400000-0x02500000 and 0x02500000-0x02600000 should be plenty.
> + * 0x02400000-0x02500000 and 0x02500000-0x02600000 should be plenty for ARM.
> + *
> + * For Aarch64, since the kernel is placed in different location,
> + * accommodate them to reserver 1M for each of them.
> *
> * On ARM, both the DTB and any possible initrd must be loaded such that they
> * fit inside the lowmem mapping in Linux. In practice, this usually means not
> @@ -62,16 +68,21 @@ dfu_alt_info+=zImage fat 0 1
> * large initrds before they start colliding with U-Boot.
> */
> #ifdef CONFIG_ARM64
> +pxefile_addr_r=0x00080000
> +scriptaddr=0x00100000
> +kernel_addr_r=0x00200000
> +fdt_addr_r=0x03400000
> +ramdisk_addr_r=0x03500000
> fdt_high=ffffffffffffffff
> initrd_high=ffffffffffffffff
> #else
> -fdt_high=ffffffff
> -initrd_high=ffffffff
> -#endif
> kernel_addr_r=0x00080000
> scriptaddr=0x02400000
> pxefile_addr_r=0x02500000
> fdt_addr_r=0x02600000
> ramdisk_addr_r=0x02700000
> +fdt_high=ffffffff
> +initrd_high=ffffffff
> +#endif
>
> boot_targets=mmc usb pxe dhcp
We need to drop the disabling of device tree / initrd relocation as
that's sure not going to help matters. What's the minimum amount of
memory an aarch64 Pi will have? I really prefer reserving 128MiB (even
if that's not the maximum Linux Kernel Image size anymore) and then
device tree and then initrd.
--
Tom
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