On 2015年01月20日 19:10, Mark Rutland wrote:
On Tue, Jan 20, 2015 at 09:29:14AM +0000, Hanjun Guo wrote:
On 2015年01月20日 02:01, Mark Rutland wrote:
On Mon, Jan 19, 2015 at 05:52:33PM +0000, Catalin Marinas wrote:
On Mon, Jan 19, 2015 at 04:59:47PM +0000, Jon Masters wrote:
On 01/19/2015 10:13 AM, Grant Likely wrote:
On Mon, 19 Jan 2015 13:51:45 +0000 , Catalin Marinas catalin.marinas@arm.com wrote: > On Mon, Jan 19, 2015 at 11:55:32AM +0000, Ard Biesheuvel wrote: >> On 19 January 2015 at 11:42, Catalin Marinas catalin.marinas@arm.com wrote: >>> On Wed, Jan 14, 2015 at 03:04:52PM +0000, Hanjun Guo wrote: >>>> From: Al Stone al.stone@linaro.org >>>> >>>> Introduce one early parameters "off" and "force" for "acpi", acpi=off >>>> will be the default behavior for ARM64, so introduce acpi=force to >>>> enable ACPI on ARM64. >>>> >>>> Disable ACPI before early parameters parsed, and enable it to pass >>>> "acpi=force" if people want use ACPI on ARM64. This ensures DT be >>>> the prefer one if ACPI table and DT both are provided at this moment. >>> [...] >>>> --- a/arch/arm64/kernel/setup.c >>>> +++ b/arch/arm64/kernel/setup.c >>>> @@ -62,6 +62,7 @@ >>>> #include <asm/memblock.h> >>>> #include <asm/psci.h> >>>> #include <asm/efi.h> >>>> +#include <asm/acpi.h> >>>> >>>> unsigned int processor_id; >>>> EXPORT_SYMBOL(processor_id); >>>> @@ -388,6 +389,8 @@ void __init setup_arch(char **cmdline_p) >>>> early_fixmap_init(); >>>> early_ioremap_init(); >>>> >>>> + disable_acpi(); >>>> + >>>> parse_early_param(); >>>> >>>> /* >>> >>> Did we get to any conclusion here? DT being the preferred one is fine >>> when both DT and ACPI are present but do we still want the kernel to >>> ignore ACPI altogether if DT is not present? It's a bit harder to detect >>> the presence of DT at this point since the EFI_STUB added one already. I >>> guess we could move the "acpi=force" argument passing to EFI_STUB if no >>> DT is present at boot. >> >> Since the EFI stub populates the /chosen node in DT, I would prefer >> for it to add a property there to indicate whether it created the DT >> from scratch rather than adding ACPI specific stuff in there (even if >> it is just a string to concatenate) > > This works for me. So we could pass "acpi=force" in EFI stub if it > created the DT from scratch *and* ACPI tables are present (can it detect > the latter? And maybe it could print something if none are available). > If that works, the actual kernel can assume that ACPI needs to be > explicitly enabled via acpi=force, irrespective of how much information > it has in DT.
Ditto for me. I think this is a fine solution. And, yes, the stub can easily detect the presence of ACPI by looking in the UEFI config table.
I get the point behind doing this, but could we not have it pass in a different parameter than =force? Perhaps something new? I'd like to separate out the case that it was enabled automatically vs explicitly forced on by a user wanting to use ACPI on a system with both tables.
Ard had a point, so we should probably not pass acpi=force from EFI stub (especially since a user may explicitly pass acpi=off irrespective of DT presence). Some other property in the chosen node? It's not even an ABI since that's a contract between EFI stub and the rest of the kernel, so an in-kernel only interface.
Not strictly true once kexec is in place. Then it becomes a stub -> kernel -> kernel -> kernel -> ... interface, alnog with the rest of the properties the stub puts in the DTB.
Having something like /chosen/linux,uefi-stub-generated-dtb sounds sane regardless.
How about the patch (just RFC, maybe it is horrible :) ) below:
When system supporting both DT and ACPI but firmware providing no dtb, we can use this linux,uefi-stub-generated-dtb property to let kernel know that we can try ACPI configuration data.
Signed-off-by: Hanjun Guo hanjun.guo@linaro.org
Documentation/devicetree/bindings/chosen.txt | 19 ++++++++++++++++ arch/arm64/kernel/setup.c | 34 +++++++++++++++++++++++++++- drivers/firmware/efi/libstub/fdt.c | 6 +++++ 3 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt index ed838f4..18776b9 100644 --- a/Documentation/devicetree/bindings/chosen.txt +++ b/Documentation/devicetree/bindings/chosen.txt @@ -44,3 +44,22 @@ Implementation note: Linux will look for the property "linux,stdout-path" or on PowerPC "stdout" if "stdout-path" is not found. However, the "linux,stdout-path" and "stdout" properties are deprecated. New platforms should only use the "stdout-path" property.
+linux,uefi-stub-generated-dtb property +--------------------------------------
+UEFI stub will generate this property in the chosen node to let linux kernel +know that there is no DTB provided by firmware.
+There is a use case for system supporting both DT and ACPI, when firmware +doesn't provide DT, we can try ACPI configration data to boot the system.
I don't think we need to list potential use cases here, this can be useful regardless of UEFI.
OK.
The other UEFI stub properties currently live under Documentation/arm/uefi.txt. This should live with them.
OK, will update in next version.
+Usage:
+linux,uefi-stub-generated-dtb = "true" means that it is true that the dtb +is generated by uefi stub
+or
+linux,uefi-stub-generated-dtb = "false" is the reverse.
I imagined this would be an empty property. It would only be present if the stub generated the DTB, and has no value:
/chosen { linux,uefi-stub-generated-dtb; };
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 54e39e3..8268c7b 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -371,6 +371,31 @@ static void __init request_standard_resources(void) } }
+int __init dt_scan_chosen(unsigned long node, const char *uname,
int depth, void *data)
+{
- const char *p;
- if (depth != 1 || !data ||
(strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
return 0;
Do we ever generate chosen@0, and do we even accept that?
Sorry, I have limited knowledge about the history of DT, so I think you meant that I just need to check strcmp(uname, "chosen") here, right?
- p = of_get_flat_dt_prop(node, "linux,uefi-stub-generated-dtb", NULL);
- if (!p && !strcmp(p, "true"))
*data = true;
- return 1;
+}
+static bool __init is_uefi_stub_generated_dtb(void) +{
- bool flag = false;
- of_scan_flat_dt(dt_scan_chosen, &flag);
- return flag;
+}
u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
void __init setup_arch(char **cmdline_p)
@@ -389,7 +414,14 @@ void __init setup_arch(char **cmdline_p) early_fixmap_init(); early_ioremap_init();
- disable_acpi();
/*
* If no dtb provided by firmware, enable ACPI
* and try to boot with ACPI configuration data
*/
if (is_uefi_stub_generated_dtb())
enable_acpi();
else
disable_acpi();
parse_early_param();
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c index c846a96..9e2084b 100644 --- a/drivers/firmware/efi/libstub/fdt.c +++ b/drivers/firmware/efi/libstub/fdt.c @@ -154,6 +154,12 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt, if (status) goto fdt_set_fail;
- /* Add a property to show the dtb is generated by uefi stub or not */
- status = fdt_setprop_string(fdt, node, "linux,uefi-stub-generated-dtb",
orig_fdt ? "false" : "true");
- if (status)
goto fdt_set_fail;
This should create an empty property, and only when generated by the stub.
OK. could you give me some guidance to use which API to create an empty property? I try to find but failed.
Thanks for the review!
Hanjun