[Qemu-devel] [PATCH] memory: Fix assertion for flash devices

[Qemu-devel] [PATCH] memory: Fix assertion for flash devices

[Stefan Weil]

There is a regression since commit c5705a7728b4a6bc9e4f2d35911adbaf28042b25
or some other recent change.

System emulation with a flash device raises an assertion in function
qemu_ram_set_idstr because no new_block is found at the requested addr.

The address of the memory region (mr->ram_addr) is set by
memory_region_init_rom_device:

    mr->ram_addr = qemu_ram_alloc(size, mr);
    mr->ram_addr |= cpu_register_io_memory(mr);

The 2nd line adds a small offset to mr->ram_addr, and this offset
makes ram_set_idstr fail with an assertion.

Masking mr->ram_addr with the target's page mask removes the small
offset and makes flash devices work again.

Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 memory.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/memory.c b/memory.c
index 394cbab..1b2f9e8 100644
--- a/memory.c
+++ b/memory.c
@@ -1386,7 +1386,7 @@ void memory_region_set_alias_offset(MemoryRegion *mr, target_phys_addr_t offset)
 
 ram_addr_t memory_region_get_ram_addr(MemoryRegion *mr)
 {
-    return mr->ram_addr;
+    return mr->ram_addr & TARGET_PAGE_MASK;
 }
 
 static int cmp_flatrange_addr(const void *addr_, const void *fr_)
-- 
1.7.0.4

Re: [Qemu-devel] [PATCH] memory: Fix assertion for flash devices

[Aurelien Jarno]

On Sat, Jan 07, 2012 at 12:13:46PM +0100, Stefan Weil wrote:
> There is a regression since commit c5705a7728b4a6bc9e4f2d35911adbaf28042b25
> or some other recent change.
> 
> System emulation with a flash device raises an assertion in function
> qemu_ram_set_idstr because no new_block is found at the requested addr.
> 
> The address of the memory region (mr->ram_addr) is set by
> memory_region_init_rom_device:
> 
>     mr->ram_addr = qemu_ram_alloc(size, mr);
>     mr->ram_addr |= cpu_register_io_memory(mr);
> 
> The 2nd line adds a small offset to mr->ram_addr, and this offset
> makes ram_set_idstr fail with an assertion.
> 
> Masking mr->ram_addr with the target's page mask removes the small
> offset and makes flash devices work again.
> 
> Cc: Avi Kivity <avi@redhat.com>
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
>  memory.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 

I can't confirm the patch is correct, but at least I can confirm it fix
the breakage.

Tested-by: Aurelien Jarno <aurelien@aurel32.net>

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

Re: [Qemu-devel] [PATCH] memory: Fix assertion for flash devices

[Avi Kivity]

On 01/07/2012 01:13 PM, Stefan Weil wrote:
> There is a regression since commit c5705a7728b4a6bc9e4f2d35911adbaf28042b25
> or some other recent change.
>
> System emulation with a flash device raises an assertion in function
> qemu_ram_set_idstr because no new_block is found at the requested addr.
>
> The address of the memory region (mr->ram_addr) is set by
> memory_region_init_rom_device:
>
>     mr->ram_addr = qemu_ram_alloc(size, mr);
>     mr->ram_addr |= cpu_register_io_memory(mr);
>
> The 2nd line adds a small offset to mr->ram_addr, and this offset
> makes ram_set_idstr fail with an assertion.
>
> Masking mr->ram_addr with the target's page mask removes the small
> offset and makes flash devices work again.
>
>
> diff --git a/memory.c b/memory.c
> index 394cbab..1b2f9e8 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1386,7 +1386,7 @@ void memory_region_set_alias_offset(MemoryRegion *mr, target_phys_addr_t offset)
>  
>  ram_addr_t memory_region_get_ram_addr(MemoryRegion *mr)
>  {
> -    return mr->ram_addr;
> +    return mr->ram_addr & TARGET_PAGE_MASK;
>  }
>  

This makes get_ram_addr() lie about the return value - it's no longer
the ram_addr.  Doesn't matter much since it's temporary, but I patched
vmstate_register_ram() instead.

-- 
error compiling committee.c: too many arguments to function