On 8/19/21 4:53 PM, Peter Hoyes wrote:
Hi,
From: Peter Hoyes Peter.Hoyes@arm.com
Use the environment variable armv8_switch_to_el1 to determine whether to switch to EL1 at runtime. This is an alternative to the CONFIG_ARMV8_SWITCH_TO_EL1 compile-time option.
This might be useful outside of the v8-R64 FVP. I cannot find CONFIG_ARMV8_SWITCH_TO_EL1 being set anywhere, which makes me wonder how this is used? Are there certain custom builds which define this somehow?
In any case forcing "kernel" entry in either EL1 or EL2, and deciding this at runtime sounds useful for certain scenarios in general, and be it for debugging and testing. So shall we get rid of this compile time option at all, or shall this be retained to avoid extra code?
The environment variable will be ineffective if the ARMV8_MULTIENTRY config is used.
This is required by the Armv8r64 architecture, which must be able to boot at S-EL1 for Linux but may need to boot at other ELs for other systems.
Signed-off-by: Peter Hoyes Peter.Hoyes@arm.com
arch/arm/lib/bootm.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-)
diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c index f60ee3a7e6..ea9bfe7570 100644 --- a/arch/arm/lib/bootm.c +++ b/arch/arm/lib/bootm.c @@ -317,7 +317,6 @@ __weak void update_os_arch_secondary_cores(uint8_t os_arch) { }
-#ifdef CONFIG_ARMV8_SWITCH_TO_EL1 static void switch_to_el1(void) { if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) && @@ -332,7 +331,6 @@ static void switch_to_el1(void) ES_TO_AARCH64); } #endif -#endif
/* Subcommand: GO */ static void boot_jump_linux(bootm_headers_t *images, int flag) @@ -359,21 +357,33 @@ static void boot_jump_linux(bootm_headers_t *images, int flag)
update_os_arch_secondary_cores(images->os.arch);-#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
armv8_switch_to_el2((u64)images->ft_addr, 0, 0, 0,(u64)switch_to_el1, ES_TO_AARCH64);+#ifdef CONFIG_ARMV8_MULTIENTRY
int armv8_switch_to_el1 = -1;
if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) &&(images->os.arch == IH_ARCH_ARM))armv8_switch_to_el2(0, (u64)gd->bd->bi_arch_number,(u64)images->ft_addr, 0,(u64)images->ep,ES_TO_AARCH32);elsearmv8_switch_to_el2((u64)images->ft_addr, 0, 0, 0,images->ep,ES_TO_AARCH64);
int armv8_switch_to_el1 = env_get_yesno("armv8_switch_to_el1");+#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
if (armv8_switch_to_el1 == -1) {armv8_switch_to_el1 = 1;}+#endif
if (armv8_switch_to_el1 == 1) {
This looks confusing. Can't we use CONFIG_IS_ENABLED() and override armv8_switch_to_el1, then use this one variable to trigger the action?
Cheers, Andre
armv8_switch_to_el2((u64)images->ft_addr, 0, 0, 0,(u64)switch_to_el1, ES_TO_AARCH64);} else {if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) &&(images->os.arch == IH_ARCH_ARM))armv8_switch_to_el2(0,(u64)gd->bd->bi_arch_number,(u64)images->ft_addr, 0,(u64)images->ep,ES_TO_AARCH32);elsearmv8_switch_to_el2((u64)images->ft_addr,0, 0, 0,images->ep,ES_TO_AARCH64);}