[PATCH] ppc64: tell firmware about kernel capabilities

On pSeries systems, according to the platform architecture specs, we are
supposed to be supplying a structure to firmware that tells firmware about
our capabilities, such as which version of the data structures that
describe available memory we are expecting to see.  The way we end up
having to supply this data structure is a bit gross, since it was designed
for AIX and doesn't suit us very well.  This patch adds the code to supply
this data structure to the firmware.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/arch/ppc64/kernel/prom_init.c b/arch/ppc64/kernel/prom_init.c
index 8dffa9ae2623..b0b784f9a4ea 100644
--- a/arch/ppc64/kernel/prom_init.c
+++ b/arch/ppc64/kernel/prom_init.c
@@ -493,6 +493,113 @@ static void __init early_cmdline_parse(void)
 }
 
 /*
+ * To tell the firmware what our capabilities are, we have to pass
+ * it a fake 32-bit ELF header containing a couple of PT_NOTE sections
+ * that contain structures that contain the actual values.
+ */
+static struct fake_elf {
+	Elf32_Ehdr	elfhdr;
+	Elf32_Phdr	phdr[2];
+	struct chrpnote {
+		u32	namesz;
+		u32	descsz;
+		u32	type;
+		char	name[8];	/* "PowerPC" */
+		struct chrpdesc {
+			u32	real_mode;
+			u32	real_base;
+			u32	real_size;
+			u32	virt_base;
+			u32	virt_size;
+			u32	load_base;
+		} chrpdesc;
+	} chrpnote;
+	struct rpanote {
+		u32	namesz;
+		u32	descsz;
+		u32	type;
+		char	name[24];	/* "IBM,RPA-Client-Config" */
+		struct rpadesc {
+			u32	lpar_affinity;
+			u32	min_rmo_size;
+			u32	min_rmo_percent;
+			u32	max_pft_size;
+			u32	splpar;
+			u32	min_load;
+			u32	new_mem_def;
+			u32	ignore_me;
+		} rpadesc;
+	} rpanote;
+} fake_elf = {
+	.elfhdr = {
+		.e_ident = { 0x7f, 'E', 'L', 'F',
+			     ELFCLASS32, ELFDATA2MSB, EV_CURRENT },
+		.e_type = ET_EXEC,	/* yeah right */
+		.e_machine = EM_PPC,
+		.e_version = EV_CURRENT,
+		.e_phoff = offsetof(struct fake_elf, phdr),
+		.e_phentsize = sizeof(Elf32_Phdr),
+		.e_phnum = 2
+	},
+	.phdr = {
+		[0] = {
+			.p_type = PT_NOTE,
+			.p_offset = offsetof(struct fake_elf, chrpnote),
+			.p_filesz = sizeof(struct chrpnote)
+		}, [1] = {
+			.p_type = PT_NOTE,
+			.p_offset = offsetof(struct fake_elf, rpanote),
+			.p_filesz = sizeof(struct rpanote)
+		}
+	},
+	.chrpnote = {
+		.namesz = sizeof("PowerPC"),
+		.descsz = sizeof(struct chrpdesc),
+		.type = 0x1275,
+		.name = "PowerPC",
+		.chrpdesc = {
+			.real_mode = ~0U,	/* ~0 means "don't care" */
+			.real_base = ~0U,
+			.real_size = ~0U,
+			.virt_base = ~0U,
+			.virt_size = ~0U,
+			.load_base = ~0U
+		},
+	},
+	.rpanote = {
+		.namesz = sizeof("IBM,RPA-Client-Config"),
+		.descsz = sizeof(struct rpadesc),
+		.type = 0x12759999,
+		.name = "IBM,RPA-Client-Config",
+		.rpadesc = {
+			.lpar_affinity = 0,
+			.min_rmo_size = 64,	/* in megabytes */
+			.min_rmo_percent = 0,
+			.max_pft_size = 48,	/* 2^48 bytes max PFT size */
+			.splpar = 1,
+			.min_load = ~0U,
+			.new_mem_def = 0
+		}
+	}
+};
+
+static void __init prom_send_capabilities(void)
+{
+	unsigned long offset = reloc_offset();
+	ihandle elfloader;
+	int ret;
+
+	elfloader = call_prom("open", 1, 1, ADDR("/packages/elf-loader"));
+	if (elfloader == 0) {
+		prom_printf("couldn't open /packages/elf-loader\n");
+		return;
+	}
+	ret = call_prom("call-method", 3, 1, ADDR("process-elf-header"),
+			elfloader, ADDR(&fake_elf));
+	call_prom("close", 1, 0, elfloader);
+}
+
+/*
  * Memory allocation strategy... our layout is normally:
  *
  *  at 14Mb or more we vmlinux, then a gap and initrd. In some rare cases, initrd