Re: [PULL 3/3] hw/loongarch: Modify flash block size to 256K

[Daniel P . Berrangé]

On Fri, Jul 19, 2024 at 10:12:20AM +0200, Philippe Mathieu-Daudé wrote:
> On 19/7/24 04:26, Song Gao wrote:
> > From: Xianglai Li <lixianglai@loongson.cn>
> > 
> > loongarch added a common library for edk2 to
> > parse flash base addresses through fdt.
> > For compatibility with other architectures,
> > the flash block size in qemu is now changed to 256k.
> > 
> > Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
> > Reviewed-by: Song Gao <gaosong@loongson.cn>
> > Message-Id: <20240624033319.999631-1-lixianglai@loongson.cn>
> > Signed-off-by: Song Gao <gaosong@loongson.cn>
> > ---
> >   include/hw/loongarch/virt.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/include/hw/loongarch/virt.h b/include/hw/loongarch/virt.h
> > index 8fdfacf268..603c1cebdb 100644
> > --- a/include/hw/loongarch/virt.h
> > +++ b/include/hw/loongarch/virt.h
> > @@ -20,7 +20,7 @@
> >   #define VIRT_FWCFG_BASE         0x1e020000UL
> >   #define VIRT_BIOS_BASE          0x1c000000UL
> >   #define VIRT_BIOS_SIZE          (16 * MiB)
> > -#define VIRT_FLASH_SECTOR_SIZE  (128 * KiB)
> > +#define VIRT_FLASH_SECTOR_SIZE  (256 * KiB)
> 
> Again, I believe this breaks machine migration. See the recent
> example Daniel explained to me:
> https://lore.kernel.org/qemu-devel/Zn6EQ39Q57KtmKPU@redhat.com/

Yes, changing flash size breaks migration compat, but note that loongarch
does not have any versioned machine types, so it has zero migration compat
right now regardles of this change. IOW, now is the right time to make the
change, before someone asks for versioned machines with loongarch.

With regards,
Daniel
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