Hi Graeme,
On Sat, Nov 17, 2012 at 5:07 PM, Graeme Russ graeme.russ@gmail.com wrote:
Hi Simon,
On 11/17/2012 08:19 AM, Simon Glass wrote:
Move this field into arch_global_data and tidy up.
This will certainly break x86, so will need Graeme's help to sort out
Yes, it most certainly will break x86 :)
the problem. I would prefer not to put the architecture-specific stuff at the top of global_data since we relying on that seems even more ugly.
The fix is not that hard though...
The whole point of putting gdt_addr at the top of the global data structure is to guarantee that is is the very fist void * in gd. The trick is how we use the 'F' segment. By loading the fs register with the physical address of gd, virtual address 0 of fs contains the address of gd.
But really, we can put the address of gd anywhere, as long as we set fs to be that address
Signed-off-by: Simon Glass sjg@chromium.org
arch/x86/cpu/cpu.c | 2 +- arch/x86/include/asm/global_data.h | 12 +++++++++--- arch/x86/lib/init_helpers.c | 2 +- 3 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c index e9bb0d7..c276aa6 100644 --- a/arch/x86/cpu/cpu.c +++ b/arch/x86/cpu/cpu.c @@ -92,7 +92,7 @@ static void load_gdt(const u64 *boot_gdt, u16 num_entries)
void init_gd(gd_t *id, u64 *gdt_addr) {
id->gd_addr = (ulong)id;
id->arch.gd_addr = (ulong)id; setup_gdt(id, gdt_addr);If the original code had been:
setup_gdt(&(id->gd_addr), gdt_addr);
There would have been no reliance on gd_addr being the first member of gd. So change this to:
setup_gdt(&(id->arch.gd_addr), gdt_addr);
And you should be pretty much set - and gd_addr can be anywhere in the arch gd.
Thanks for that. I actually understand it now, for better or worse. It seems to work fine. Actually your clean-up of the global_data really has paid dividends as things are so much nicer now.
I'm going to resend the whole series rebased to master.
Regards, Simon
}
diff --git a/arch/x86/include/asm/global_data.h b/arch/x86/include/asm/global_data.h index 3df83bb..d2eb00a 100644 --- a/arch/x86/include/asm/global_data.h +++ b/arch/x86/include/asm/global_data.h @@ -28,8 +28,16 @@
/* Architecture-specific global data */ struct arch_global_data {
unsigned long gdt_addr; /* Location of GDT */
/** NOTE: gd_addr MUST be first member of struct global_data!** But it now isn't, so this is sure to break x86. Can we change* x86 to not require this? I don't think we should put the* arch data first in global_data...*/Yes we can - see above
unsigned long new_gd_addr; /* New location of Global Data */
unsigned long gd_addr; /* Location of Global Data */unsigned long gdt_addr; /* Location of GDT */};
/* @@ -41,8 +49,6 @@ struct arch_global_data { */
typedef struct global_data {
/* NOTE: gd_addr MUST be first member of struct global_data! */unsigned long gd_addr; /* Location of Global Data */ bd_t *bd; unsigned long flags; unsigned int baudrate;diff --git a/arch/x86/lib/init_helpers.c b/arch/x86/lib/init_helpers.c index 05cadcd..ac789c2 100644 --- a/arch/x86/lib/init_helpers.c +++ b/arch/x86/lib/init_helpers.c @@ -126,7 +126,7 @@ int copy_gd_to_ram_f_r(void) * in-RAM copy of Global Data (calculate_relocation_address() * has already calculated the in-RAM location of the GDT) */
ram_gd->gd_addr = (ulong)ram_gd;
ram_gd->arch.gd_addr = (ulong)ram_gd; init_gd(ram_gd, (u64 *)gd->arch.gdt_addr); return 0;Regards,
Graeme