Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-08 Thread Stefano Stabellini
On Wed, 8 Feb 2017, Julien Grall wrote: > Commit 146786b "efi: create efi_enabled()" introduced a variable > efi_flags stored in BSS and used to pass information between the stub > and Xen. However on ARM, BSS is zeroed after the stub has finished to > run and before Xen is started. This means that

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-08 Thread Daniel Kiper
On Wed, Feb 08, 2017 at 10:48:14AM +, Julien Grall wrote: > Commit 146786b "efi: create efi_enabled()" introduced a variable > efi_flags stored in BSS and used to pass information between the stub > and Xen. However on ARM, BSS is zeroed after the stub has finished to > run and before Xen is st

[Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-08 Thread Julien Grall
Commit 146786b "efi: create efi_enabled()" introduced a variable efi_flags stored in BSS and used to pass information between the stub and Xen. However on ARM, BSS is zeroed after the stub has finished to run and before Xen is started. This means that the bits set in efi_flags will be lost. We wer

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Julien Grall
Hi Stefano, On 03/02/17 19:14, Stefano Stabellini wrote: On Fri, 3 Feb 2017, Julien Grall wrote: Hi Stefano, On 02/02/17 23:25, Stefano Stabellini wrote: On Thu, 2 Feb 2017, Julien Grall wrote: --- xen/arch/arm/arm64/head.S | 23 +++ 1 file changed, 19 insertions(+), 4 d

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Stefano Stabellini
On Fri, 3 Feb 2017, Julien Grall wrote: > Hi Stefano, > > On 02/02/17 23:25, Stefano Stabellini wrote: > > On Thu, 2 Feb 2017, Julien Grall wrote: > > > --- > > > xen/arch/arm/arm64/head.S | 23 +++ > > > 1 file changed, 19 insertions(+), 4 deletions(-) > > > > > > diff --git

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Julien Grall
Hi Stefano, On 02/02/17 23:25, Stefano Stabellini wrote: On Thu, 2 Feb 2017, Julien Grall wrote: --- xen/arch/arm/arm64/head.S | 23 +++ 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index 3f63d2a..8cb46

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Jan Beulich
>>> On 03.02.17 at 15:35, wrote: > On 03/02/17 14:31, Jan Beulich wrote: > On 03.02.17 at 15:24, wrote: >>> On 03/02/17 07:41, Jan Beulich wrote: >>> On 02.02.17 at 20:25, wrote: > @@ -261,6 +265,8 @@ GLOBAL(init_secondary) > sub x20, x19, x0 /* x20 := phys-o

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Julien Grall
On 03/02/17 14:31, Jan Beulich wrote: On 03.02.17 at 15:24, wrote: On 03/02/17 07:41, Jan Beulich wrote: On 02.02.17 at 20:25, wrote: @@ -261,6 +265,8 @@ GLOBAL(init_secondary) sub x20, x19, x0 /* x20 := phys-offset */ mov x22, #1/* x22 := i

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Jan Beulich
>>> On 03.02.17 at 15:24, wrote: > On 03/02/17 07:41, Jan Beulich wrote: > On 02.02.17 at 20:25, wrote: >>> @@ -261,6 +265,8 @@ GLOBAL(init_secondary) >>> sub x20, x19, x0 /* x20 := phys-offset */ >>> >>> mov x22, #1/* x22 := is_secondary_cpu */

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-03 Thread Julien Grall
Hi Jan, On 03/02/17 07:41, Jan Beulich wrote: On 02.02.17 at 20:25, wrote: @@ -261,6 +265,8 @@ GLOBAL(init_secondary) sub x20, x19, x0 /* x20 := phys-offset */ mov x22, #1/* x22 := is_secondary_cpu */ +/* Skip zero BSS on secondary CPUs

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-02 Thread Jan Beulich
>>> On 02.02.17 at 20:25, wrote: > @@ -261,6 +265,8 @@ GLOBAL(init_secondary) > sub x20, x19, x0 /* x20 := phys-offset */ > > mov x22, #1/* x22 := is_secondary_cpu */ > +/* Skip zero BSS on secondary CPUs to avoid nasty surprises. */ > +

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-02 Thread Andrew Cooper
On 02/02/2017 23:25, Stefano Stabellini wrote: > On Thu, 2 Feb 2017, Julien Grall wrote: >> Commit 146786b "efi: create efi_enabled()" introduced a variable >> efi_flags stored in BSS and used to pass information between the stub >> and Xen. However on ARM, BSS is zeroed after the stub has finished

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-02 Thread Stefano Stabellini
On Thu, 2 Feb 2017, Julien Grall wrote: > Commit 146786b "efi: create efi_enabled()" introduced a variable > efi_flags stored in BSS and used to pass information between the stub > and Xen. However on ARM, BSS is zeroed after the stub has finished to > run and before Xen is started. This means that

Re: [Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-02 Thread Daniel Kiper
On Thu, Feb 02, 2017 at 07:25:32PM +, Julien Grall wrote: > Commit 146786b "efi: create efi_enabled()" introduced a variable > efi_flags stored in BSS and used to pass information between the stub > and Xen. However on ARM, BSS is zeroed after the stub has finished to > run and before Xen is st

[Xen-devel] [PATCH] xen/arm64: Don't zero BSS when booting using EFI

2017-02-02 Thread Julien Grall
Commit 146786b "efi: create efi_enabled()" introduced a variable efi_flags stored in BSS and used to pass information between the stub and Xen. However on ARM, BSS is zeroed after the stub has finished to run and before Xen is started. This means that the bits set in efi_flags will be lost. We wer