| Message ID | 20221104100741.2176307-4-wei.chen@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen/arm: Add Armv8-R64 MPU support to Xen - Part#1 | expand |
Hi Wei, On 04/11/2022 10:07, Wei Chen wrote: > Current EFI boot services support of Arm64 could not > work well for Armv8-R64 system that only has MPU in > EL2. That is because EFI boot services may need some > relocation support or partial PIE/PIC support. I am a bit confused with argument. We have nothing in Xen today to deal with relocation/partial PIE/PIC support. So what is the exact problem? Is it because UEFI can load Xen anywwhere? > But these will not be supported in the initial stage of > porting Xen to MPU systems. So in this patch, we > disable EFI boot services support for Arm MPU systems. > > Signed-off-by: Wei Chen <wei.chen@arm.com> > --- > xen/arch/arm/Kconfig | 2 +- > xen/arch/arm/arm64/head.S | 8 ++++++-- > 2 files changed, 7 insertions(+), 3 deletions(-) > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig > index 1fe5faf847..ad592367bd 100644 > --- a/xen/arch/arm/Kconfig > +++ b/xen/arch/arm/Kconfig > @@ -7,7 +7,7 @@ config ARM_64 > def_bool y > depends on !ARM_32 > select 64BIT > - select ARM_EFI > + select ARM_EFI if !HAS_MPU I think it would make sense to allow ARM_EFI to be disabled even without the MPU support. So this would remove nearly 3K lines (just using wc -l *.c in the efi directories) for someone that don't need to boot using EFI. > select HAS_FAST_MULTIPLY > > config ARM > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S > index ad014716db..ccedf20dc7 100644 > --- a/xen/arch/arm/arm64/head.S > +++ b/xen/arch/arm/arm64/head.S > @@ -172,8 +172,10 @@ efi_head: > .byte 0x52 > .byte 0x4d > .byte 0x64 > - .long pe_header - efi_head /* Offset to the PE header. */ > - > +#ifndef CONFIG_ARM_EFI > + .long 0 /* 0 means no PE header. */ > +#else > + .long pe_header - efi_head /* Offset to the PE header. */ > /* > * Add the PE/COFF header to the file. The address of this header > * is at offset 0x3c in the file, and is part of Linux "Image" > @@ -279,6 +281,8 @@ section_table: > .short 0 /* NumberOfLineNumbers (0 for executables) */ > .long 0xe0500020 /* Characteristics (section flags) */ > .align 5 > +#endif /* CONFIG_ARM_EFI */ > + > real_start: > /* BSS should be zeroed when booting without EFI */ > mov x26, #0 /* x26 := skip_zero_bss */ Shouldn't the function efi_xen_start be stubbed as well? Cheers,
On 06/11/2022 19:12, Julien Grall wrote: > Hi Wei, > > On 04/11/2022 10:07, Wei Chen wrote: >> Current EFI boot services support of Arm64 could not >> work well for Armv8-R64 system that only has MPU in >> EL2. That is because EFI boot services may need some >> relocation support or partial PIE/PIC support. > > I am a bit confused with argument. We have nothing in Xen today to deal > with relocation/partial PIE/PIC support. So what is the exact problem? > Is it because UEFI can load Xen anywwhere? > >> But these will not be supported in the initial stage of >> porting Xen to MPU systems. So in this patch, we >> disable EFI boot services support for Arm MPU systems. >> >> Signed-off-by: Wei Chen <wei.chen@arm.com> >> --- >> xen/arch/arm/Kconfig | 2 +- >> xen/arch/arm/arm64/head.S | 8 ++++++-- >> 2 files changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig >> index 1fe5faf847..ad592367bd 100644 >> --- a/xen/arch/arm/Kconfig >> +++ b/xen/arch/arm/Kconfig >> @@ -7,7 +7,7 @@ config ARM_64 >> def_bool y >> depends on !ARM_32 >> select 64BIT >> - select ARM_EFI >> + select ARM_EFI if !HAS_MPU > > I think it would make sense to allow ARM_EFI to be disabled even without > the MPU support. So this would remove nearly 3K lines (just using wc -l > *.c in the efi directories) for someone that don't need to boot using EFI. > >> select HAS_FAST_MULTIPLY >> config ARM >> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S >> index ad014716db..ccedf20dc7 100644 >> --- a/xen/arch/arm/arm64/head.S >> +++ b/xen/arch/arm/arm64/head.S >> @@ -172,8 +172,10 @@ efi_head: >> .byte 0x52 >> .byte 0x4d >> .byte 0x64 >> - .long pe_header - efi_head /* Offset to the PE >> header. */ >> - >> +#ifndef CONFIG_ARM_EFI >> + .long 0 /* 0 means no PE header. */ >> +#else >> + .long pe_header - efi_head /* Offset to the PE header. */ >> /* >> * Add the PE/COFF header to the file. The address of this >> header >> * is at offset 0x3c in the file, and is part of Linux "Image" >> @@ -279,6 +281,8 @@ section_table: >> .short 0 /* NumberOfLineNumbers (0 for >> executables) */ >> .long 0xe0500020 /* Characteristics (section flags) */ >> .align 5 >> +#endif /* CONFIG_ARM_EFI */ >> + >> real_start: >> /* BSS should be zeroed when booting without EFI */ >> mov x26, #0 /* x26 := skip_zero_bss */ > > Shouldn't the function efi_xen_start be stubbed as well? Sorry, I mean protected rather than stubbed because there will be no user when !CONFIG_ARM_EFI. Cheers,
Hi Julien, > -----Original Message----- > From: Julien Grall <julien@xen.org> > Sent: 2022年11月7日 3:12 > To: Wei Chen <Wei.Chen@arm.com>; xen-devel@lists.xenproject.org > Cc: nd <nd@arm.com>; Stefano Stabellini <sstabellini@kernel.org>; Bertrand > Marquis <Bertrand.Marquis@arm.com>; Volodymyr Babchuk > <Volodymyr_Babchuk@epam.com> > Subject: Re: [PATCH v6 03/11] xen/arm: disable EFI boot services for MPU > systems > > Hi Wei, > > On 04/11/2022 10:07, Wei Chen wrote: > > Current EFI boot services support of Arm64 could not > > work well for Armv8-R64 system that only has MPU in > > EL2. That is because EFI boot services may need some > > relocation support or partial PIE/PIC support. > > I am a bit confused with argument. We have nothing in Xen today to deal > with relocation/partial PIE/PIC support. So what is the exact problem? > Is it because UEFI can load Xen anywwhere? > > > But these will not be supported in the initial stage of > > porting Xen to MPU systems. So in this patch, we > > disable EFI boot services support for Arm MPU systems. > > > > Signed-off-by: Wei Chen <wei.chen@arm.com> > > --- > > xen/arch/arm/Kconfig | 2 +- > > xen/arch/arm/arm64/head.S | 8 ++++++-- > > 2 files changed, 7 insertions(+), 3 deletions(-) > > > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig > > index 1fe5faf847..ad592367bd 100644 > > --- a/xen/arch/arm/Kconfig > > +++ b/xen/arch/arm/Kconfig > > @@ -7,7 +7,7 @@ config ARM_64 > > def_bool y > > depends on !ARM_32 > > select 64BIT > > - select ARM_EFI > > + select ARM_EFI if !HAS_MPU > > I think it would make sense to allow ARM_EFI to be disabled even without > the MPU support. So this would remove nearly 3K lines (just using wc -l > *.c in the efi directories) for someone that don't need to boot using EFI. > Ok, how about address this comment in NUMA patch set#3 (Arm implementation), because about making ARM_EFI invisible to users, we had some discussions for NUMA RFC and V1. > > select HAS_FAST_MULTIPLY > > > > config ARM > > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S > > index ad014716db..ccedf20dc7 100644 > > --- a/xen/arch/arm/arm64/head.S > > +++ b/xen/arch/arm/arm64/head.S > > @@ -172,8 +172,10 @@ efi_head: > > .byte 0x52 > > .byte 0x4d > > .byte 0x64 > > - .long pe_header - efi_head /* Offset to the PE header. > */ > > - > > +#ifndef CONFIG_ARM_EFI > > + .long 0 /* 0 means no PE header. */ > > +#else > > + .long pe_header - efi_head /* Offset to the PE header. */ > > /* > > * Add the PE/COFF header to the file. The address of this > header > > * is at offset 0x3c in the file, and is part of Linux "Image" > > @@ -279,6 +281,8 @@ section_table: > > .short 0 /* NumberOfLineNumbers (0 for > executables) */ > > .long 0xe0500020 /* Characteristics (section flags) */ > > .align 5 > > +#endif /* CONFIG_ARM_EFI */ > > + > > real_start: > > /* BSS should be zeroed when booting without EFI */ > > mov x26, #0 /* x26 := skip_zero_bss */ > > Shouldn't the function efi_xen_start be stubbed as well? > Reply for your next email: Yes, this is a good point, efi_xen_start should be protected. I will fix it. Cheers, Wei Chen > Cheers, > > -- > Julien Grall
Hi Julien, On 2022/11/7 3:12, Julien Grall wrote: > Hi Wei, > > On 04/11/2022 10:07, Wei Chen wrote: >> Current EFI boot services support of Arm64 could not >> work well for Armv8-R64 system that only has MPU in >> EL2. That is because EFI boot services may need some >> relocation support or partial PIE/PIC support. > > I am a bit confused with argument. We have nothing in Xen today to deal > with relocation/partial PIE/PIC support. So what is the exact problem? > Is it because UEFI can load Xen anywwhere? > Sorry, I had missed this comment. Yes, you're right we had tried to boot Xen R82 Image from EFI loader, but it failed. UEFI loader will load Xen to a random address, which is not supported by Xen R82 now. Cheers, Wei Chen >> But these will not be supported in the initial stage of >> porting Xen to MPU systems. So in this patch, we >> disable EFI boot services support for Arm MPU systems. >>
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index 1fe5faf847..ad592367bd 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -7,7 +7,7 @@ config ARM_64 def_bool y depends on !ARM_32 select 64BIT - select ARM_EFI + select ARM_EFI if !HAS_MPU select HAS_FAST_MULTIPLY config ARM diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index ad014716db..ccedf20dc7 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -172,8 +172,10 @@ efi_head: .byte 0x52 .byte 0x4d .byte 0x64 - .long pe_header - efi_head /* Offset to the PE header. */ - +#ifndef CONFIG_ARM_EFI + .long 0 /* 0 means no PE header. */ +#else + .long pe_header - efi_head /* Offset to the PE header. */ /* * Add the PE/COFF header to the file. The address of this header * is at offset 0x3c in the file, and is part of Linux "Image" @@ -279,6 +281,8 @@ section_table: .short 0 /* NumberOfLineNumbers (0 for executables) */ .long 0xe0500020 /* Characteristics (section flags) */ .align 5 +#endif /* CONFIG_ARM_EFI */ + real_start: /* BSS should be zeroed when booting without EFI */ mov x26, #0 /* x26 := skip_zero_bss */
Current EFI boot services support of Arm64 could not work well for Armv8-R64 system that only has MPU in EL2. That is because EFI boot services may need some relocation support or partial PIE/PIC support. But these will not be supported in the initial stage of porting Xen to MPU systems. So in this patch, we disable EFI boot services support for Arm MPU systems. Signed-off-by: Wei Chen <wei.chen@arm.com> --- xen/arch/arm/Kconfig | 2 +- xen/arch/arm/arm64/head.S | 8 ++++++-- 2 files changed, 7 insertions(+), 3 deletions(-)