[Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Alexander Graf]

Linux changed its physical address location in the elf header from
0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
with the -kernel option.

This patch assures that the lowest segment in the elf binary is loaded
to KERNEL_LOAD_ADDR, which is where the firmware expects it.

With this patch applied, I was able to successfully boot a 2.6.18 and
a 2.6.27 Linux kernel using the -kernel option.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 hw/ppc_oldworld.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
index 042a40f..f64884b 100644
--- a/hw/ppc_oldworld.c
+++ b/hw/ppc_oldworld.c
@@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t ram_size, int vga_ram_size,
     }
 
     if (linux_boot) {
+        uint64_t lowaddr = 0;
         kernel_base = KERNEL_LOAD_ADDR;
         /* now we can load the kernel */
-        kernel_size = load_elf(kernel_filename, kernel_base - 0xc0000000ULL,
+        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
+        kernel_size = load_elf(kernel_filename, kernel_base - lowaddr,
                                NULL, NULL, NULL);
         if (kernel_size < 0)
             kernel_size = load_aout(kernel_filename, kernel_base,
-- 
1.6.0.2

Re: [Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Edgar E. Iglesias]

On Sun, Jan 25, 2009 at 12:54:27PM +0100, Alexander Graf wrote:
> Linux changed its physical address location in the elf header from
> 0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
> with the -kernel option.
> 
> This patch assures that the lowest segment in the elf binary is loaded
> to KERNEL_LOAD_ADDR, which is where the firmware expects it.
> 
> With this patch applied, I was able to successfully boot a 2.6.18 and
> a 2.6.27 Linux kernel using the -kernel option.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  hw/ppc_oldworld.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
> index 042a40f..f64884b 100644
> --- a/hw/ppc_oldworld.c
> +++ b/hw/ppc_oldworld.c
> @@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t ram_size, int vga_ram_size,
>      }
>  
>      if (linux_boot) {
> +        uint64_t lowaddr = 0;
>          kernel_base = KERNEL_LOAD_ADDR;
>          /* now we can load the kernel */
> -        kernel_size = load_elf(kernel_filename, kernel_base - 0xc0000000ULL,
> +        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
> +        kernel_size = load_elf(kernel_filename, kernel_base - lowaddr,
>                                 NULL, NULL, NULL);

Hello,

Can't you speculatively load at kernel_base assuming it's a new kernel,
then only if lowaddr indicates it was an old kernel you do the second
load to fix things up?

Maybe also a comment or two in the code explaining the hack.. :)

Cheers

Re: [Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Alexander Graf]

On 25.01.2009, at 15:19, Edgar E. Iglesias wrote:

> On Sun, Jan 25, 2009 at 12:54:27PM +0100, Alexander Graf wrote:
>> Linux changed its physical address location in the elf header from
>> 0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
>> with the -kernel option.
>>
>> This patch assures that the lowest segment in the elf binary is  
>> loaded
>> to KERNEL_LOAD_ADDR, which is where the firmware expects it.
>>
>> With this patch applied, I was able to successfully boot a 2.6.18 and
>> a 2.6.27 Linux kernel using the -kernel option.
>>
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>> ---
>> hw/ppc_oldworld.c |    4 +++-
>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
>> index 042a40f..f64884b 100644
>> --- a/hw/ppc_oldworld.c
>> +++ b/hw/ppc_oldworld.c
>> @@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t  
>> ram_size, int vga_ram_size,
>>     }
>>
>>     if (linux_boot) {
>> +        uint64_t lowaddr = 0;
>>         kernel_base = KERNEL_LOAD_ADDR;
>>         /* now we can load the kernel */
>> -        kernel_size = load_elf(kernel_filename, kernel_base -  
>> 0xc0000000ULL,
>> +        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
>> +        kernel_size = load_elf(kernel_filename, kernel_base -  
>> lowaddr,
>>                                NULL, NULL, NULL);
>
> Hello,
>
> Can't you speculatively load at kernel_base assuming it's a new  
> kernel,
> then only if lowaddr indicates it was an old kernel you do the second
> load to fix things up?

Hm - so we only call load_elf once for new kernels? Sounds like a good  
idea :-).

> Maybe also a comment or two in the code explaining the hack.. :)

Right, that might be nice.

Alex

>
>
> Cheers

Re: [Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Edgar E. Iglesias]

On Sun, Jan 25, 2009 at 03:22:25PM +0100, Alexander Graf wrote:
>
> On 25.01.2009, at 15:19, Edgar E. Iglesias wrote:
>
>> On Sun, Jan 25, 2009 at 12:54:27PM +0100, Alexander Graf wrote:
>>> Linux changed its physical address location in the elf header from
>>> 0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
>>> with the -kernel option.
>>>
>>> This patch assures that the lowest segment in the elf binary is loaded
>>> to KERNEL_LOAD_ADDR, which is where the firmware expects it.
>>>
>>> With this patch applied, I was able to successfully boot a 2.6.18 and
>>> a 2.6.27 Linux kernel using the -kernel option.
>>>
>>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>> ---
>>> hw/ppc_oldworld.c |    4 +++-
>>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
>>> index 042a40f..f64884b 100644
>>> --- a/hw/ppc_oldworld.c
>>> +++ b/hw/ppc_oldworld.c
>>> @@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t ram_size, 
>>> int vga_ram_size,
>>>     }
>>>
>>>     if (linux_boot) {
>>> +        uint64_t lowaddr = 0;
>>>         kernel_base = KERNEL_LOAD_ADDR;
>>>         /* now we can load the kernel */
>>> -        kernel_size = load_elf(kernel_filename, kernel_base - 
>>> 0xc0000000ULL,
>>> +        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
>>> +        kernel_size = load_elf(kernel_filename, kernel_base - lowaddr,
>>>                                NULL, NULL, NULL);
>>
>> Hello,
>>
>> Can't you speculatively load at kernel_base assuming it's a new kernel,
>> then only if lowaddr indicates it was an old kernel you do the second
>> load to fix things up?
>
> Hm - so we only call load_elf once for new kernels? Sounds like a good idea 
> :-).

Yes, if it works :)

Cheers

Re: [Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Aurelien Jarno]

On Sun, Jan 25, 2009 at 03:22:25PM +0100, Alexander Graf wrote:
>
> On 25.01.2009, at 15:19, Edgar E. Iglesias wrote:
>
>> On Sun, Jan 25, 2009 at 12:54:27PM +0100, Alexander Graf wrote:
>>> Linux changed its physical address location in the elf header from
>>> 0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
>>> with the -kernel option.
>>>
>>> This patch assures that the lowest segment in the elf binary is  
>>> loaded
>>> to KERNEL_LOAD_ADDR, which is where the firmware expects it.
>>>
>>> With this patch applied, I was able to successfully boot a 2.6.18 and
>>> a 2.6.27 Linux kernel using the -kernel option.
>>>
>>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>> ---
>>> hw/ppc_oldworld.c |    4 +++-
>>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
>>> index 042a40f..f64884b 100644
>>> --- a/hw/ppc_oldworld.c
>>> +++ b/hw/ppc_oldworld.c
>>> @@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t  
>>> ram_size, int vga_ram_size,
>>>     }
>>>
>>>     if (linux_boot) {
>>> +        uint64_t lowaddr = 0;
>>>         kernel_base = KERNEL_LOAD_ADDR;
>>>         /* now we can load the kernel */
>>> -        kernel_size = load_elf(kernel_filename, kernel_base -  
>>> 0xc0000000ULL,
>>> +        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
>>> +        kernel_size = load_elf(kernel_filename, kernel_base -  
>>> lowaddr,
>>>                                NULL, NULL, NULL);
>>
>> Hello,
>>
>> Can't you speculatively load at kernel_base assuming it's a new  
>> kernel,
>> then only if lowaddr indicates it was an old kernel you do the second
>> load to fix things up?
>
> Hm - so we only call load_elf once for new kernels? Sounds like a good  
> idea :-).
>
>> Maybe also a comment or two in the code explaining the hack.. :)
>
> Right, that might be nice.
>

I have just committed a fix based on your patch and implementing that. I
also added a comment explaining the hack.

Aurelien

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net

Re: [Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Alexander Graf]

On 26.01.2009, at 11:22, Aurelien Jarno wrote:

> On Sun, Jan 25, 2009 at 03:22:25PM +0100, Alexander Graf wrote:
>>
>> On 25.01.2009, at 15:19, Edgar E. Iglesias wrote:
>>
>>> On Sun, Jan 25, 2009 at 12:54:27PM +0100, Alexander Graf wrote:
>>>> Linux changed its physical address location in the elf header from
>>>> 0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
>>>> with the -kernel option.
>>>>
>>>> This patch assures that the lowest segment in the elf binary is
>>>> loaded
>>>> to KERNEL_LOAD_ADDR, which is where the firmware expects it.
>>>>
>>>> With this patch applied, I was able to successfully boot a 2.6.18  
>>>> and
>>>> a 2.6.27 Linux kernel using the -kernel option.
>>>>
>>>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>>> ---
>>>> hw/ppc_oldworld.c |    4 +++-
>>>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
>>>> index 042a40f..f64884b 100644
>>>> --- a/hw/ppc_oldworld.c
>>>> +++ b/hw/ppc_oldworld.c
>>>> @@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t
>>>> ram_size, int vga_ram_size,
>>>>    }
>>>>
>>>>    if (linux_boot) {
>>>> +        uint64_t lowaddr = 0;
>>>>        kernel_base = KERNEL_LOAD_ADDR;
>>>>        /* now we can load the kernel */
>>>> -        kernel_size = load_elf(kernel_filename, kernel_base -
>>>> 0xc0000000ULL,
>>>> +        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
>>>> +        kernel_size = load_elf(kernel_filename, kernel_base -
>>>> lowaddr,
>>>>                               NULL, NULL, NULL);
>>>
>>> Hello,
>>>
>>> Can't you speculatively load at kernel_base assuming it's a new
>>> kernel,
>>> then only if lowaddr indicates it was an old kernel you do the  
>>> second
>>> load to fix things up?
>>
>> Hm - so we only call load_elf once for new kernels? Sounds like a  
>> good
>> idea :-).
>>
>>> Maybe also a comment or two in the code explaining the hack.. :)
>>
>> Right, that might be nice.
>>
>
> I have just committed a fix based on your patch and implementing  
> that. I
> also added a comment explaining the hack.

Heh - I literally started to look at the patch again about 2 seconds  
before your mail came in.

Thanks!

Alex