Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Zachary Amsden wrote: Avi Kivity wrote: We haven't seen any issue with the 2.6.22 boot decompressor. Which of the four (fs, gs, ldt, or tr) were proving problematic and why? It was tr that was affecting Workstation, since we boot through normal BIOS path, and only a 16-bit task was loaded at this point. Ah. Maybe we didn't have an exit while we were in long mode with the 16-bit tss, so VT didn't notice the illegal combination. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Avi Kivity wrote: We haven't seen any issue with the 2.6.22 boot decompressor. Which of the four (fs, gs, ldt, or tr) were proving problematic and why? It was tr that was affecting Workstation, since we boot through normal BIOS path, and only a 16-bit task was loaded at this point. Just to make the state comprehensive, I opted to reload everything. Zach - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Zachary Amsden wrote: Since I was just involved in the boot decompressor for another bug, I took a look at this. 2.6.22 switches it to be 64-bit code. VT is very picky about what state it can run in. Not using VT on Intel 64-bit hardware cripples performance, running at far below normal speed, and taking minutes to decompress the kernel, which is nearly instantaneous otherwise. To get back into VT in this case, not only do we need to load FS and GS, we also need to setup an initial LDT and task. Can you try the attached patch and see that it does the right thing? I've also cc'd the KVM developers, as the same problem will affect them, and hopefully the same patch will fix it. We haven't seen any issue with the 2.6.22 boot decompressor. Which of the four (fs, gs, ldt, or tr) were proving problematic and why? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Zachary Amsden wrote: Since I was just involved in the boot decompressor for another bug, I took a look at this. 2.6.22 switches it to be 64-bit code. VT is very picky about what state it can run in. Not using VT on Intel 64-bit hardware cripples performance, running at far below normal speed, and taking minutes to decompress the kernel, which is nearly instantaneous otherwise. To get back into VT in this case, not only do we need to load FS and GS, we also need to setup an initial LDT and task. Can you try the attached patch and see that it does the right thing? I've also cc'd the KVM developers, as the same problem will affect them, and hopefully the same patch will fix it. We haven't seen any issue with the 2.6.22 boot decompressor. Which of the four (fs, gs, ldt, or tr) were proving problematic and why? - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Avi Kivity wrote: We haven't seen any issue with the 2.6.22 boot decompressor. Which of the four (fs, gs, ldt, or tr) were proving problematic and why? It was tr that was affecting Workstation, since we boot through normal BIOS path, and only a 16-bit task was loaded at this point. Just to make the state comprehensive, I opted to reload everything. Zach - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Zachary Amsden wrote: Avi Kivity wrote: We haven't seen any issue with the 2.6.22 boot decompressor. Which of the four (fs, gs, ldt, or tr) were proving problematic and why? It was tr that was affecting Workstation, since we boot through normal BIOS path, and only a 16-bit task was loaded at this point. Ah. Maybe we didn't have an exit while we were in long mode with the 16-bit tss, so VT didn't notice the illegal combination. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
On 08/04/2007 6:23:00 PM +0200, Zachary Amsden <[EMAIL PROTECTED]> wrote:
Gabriel Barazer wrote:
Hi,
After upgrading kernel to 2.6.22 on a Vmware workstation guest version
5.5 and 6 , the kernel decompression stage ("Decompressing Linux...")
is hanging for a very long time (~5 minutes) before finally
succeeding (displaying "done.\nBooting the kernel.\n"). During this
time, the VM process is eating all the CPU time during the
decompression, like an infinite loop.
Between these 2 strings is the gunzip() function at
boot/compressed/misc.c which does the real job, and the problem seemed
to appear since commit 1ab60e0f72f71ec54831e525a3e1154f1c092408.
(2.6.22-rc1 hangs, 2.6.21.6 works). The problem occurs with or without
CONFIG_RELOCATABLE enabled.
What are the possible solutions to confirm where the problem is coming
from ?
Since I was just involved in the boot decompressor for another bug, I
took a look at this. 2.6.22 switches it to be 64-bit code. VT is very
picky about what state it can run in. Not using VT on Intel 64-bit
hardware cripples performance, running at far below normal speed, and
taking minutes to decompress the kernel, which is nearly instantaneous
otherwise.
To get back into VT in this case, not only do we need to load FS and GS,
we also need to setup an initial LDT and task. Can you try the attached
patch and see that it does the right thing?
It Works (tm) ! Tried compiling with and without the patch, with exactly
the same config, just to be sure. Decompressing the kernel is now
lightning fast.
Thanks !
I've also cc'd the KVM developers, as the same problem will affect them,
and hopefully the same patch will fix it.
VT is very picky about when it can enter execution.
Get all segments setup and get LDT and TR into valid state to allow
VT execution under VMware and KVM (untested).
This makes the boot decompression run under VT, which makes it several
orders of magnitude faster on 64-bit Intel hardware.
Before, I was seeing times up to a minute or more to decompress a 1.3MB kernel
on a very fast box.
Signed-off-by: Zachary Amsden <[EMAIL PROTECTED]>
===
--- a/arch/x86_64/boot/compressed/head.S
+++ a/arch/x86_64/boot/compressed/head.S
@@ -195,6 +195,11 @@
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
+ movl %eax, %fs
+ movl %eax, %gs
+ lldt %ax
+ movl$0x20, %eax
+ ltr %ax
/* Compute the decompressed kernel start address. It is where
* we were loaded at aligned to a 2M boundary. %rbp contains the
@@ -295,6 +300,8 @@
.quad 0x /* NULL descriptor */
.quad 0x00af9a00 /* __KERNEL_CS */
.quad 0x00cf9200 /* __KERNEL_DS */
+ .quad 0x00808900 /* TS descriptor */
+ .quad 0x /* TS continued */
gdt_end:
.bss
/* Stack for uncompression */
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Gabriel Barazer wrote:
Hi,
After upgrading kernel to 2.6.22 on a Vmware workstation guest version
5.5 and 6 , the kernel decompression stage ("Decompressing Linux...")
is hanging for a very long time (~5 minutes) before finally
succeeding (displaying "done.\nBooting the kernel.\n"). During this
time, the VM process is eating all the CPU time during the
decompression, like an infinite loop.
Between these 2 strings is the gunzip() function at
boot/compressed/misc.c which does the real job, and the problem seemed
to appear since commit 1ab60e0f72f71ec54831e525a3e1154f1c092408.
(2.6.22-rc1 hangs, 2.6.21.6 works). The problem occurs with or without
CONFIG_RELOCATABLE enabled.
What are the possible solutions to confirm where the problem is coming
from ?
Since I was just involved in the boot decompressor for another bug, I
took a look at this. 2.6.22 switches it to be 64-bit code. VT is very
picky about what state it can run in. Not using VT on Intel 64-bit
hardware cripples performance, running at far below normal speed, and
taking minutes to decompress the kernel, which is nearly instantaneous
otherwise.
To get back into VT in this case, not only do we need to load FS and GS,
we also need to setup an initial LDT and task. Can you try the attached
patch and see that it does the right thing?
I've also cc'd the KVM developers, as the same problem will affect them,
and hopefully the same patch will fix it.
Thanks, Zach
Zach
VT is very picky about when it can enter execution.
Get all segments setup and get LDT and TR into valid state to allow
VT execution under VMware and KVM (untested).
This makes the boot decompression run under VT, which makes it several
orders of magnitude faster on 64-bit Intel hardware.
Before, I was seeing times up to a minute or more to decompress a 1.3MB kernel
on a very fast box.
Signed-off-by: Zachary Amsden <[EMAIL PROTECTED]>
===
--- a/arch/x86_64/boot/compressed/head.S
+++ a/arch/x86_64/boot/compressed/head.S
@@ -195,6 +195,11 @@
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
+ movl %eax, %fs
+ movl %eax, %gs
+ lldt %ax
+ movl$0x20, %eax
+ ltr %ax
/* Compute the decompressed kernel start address. It is where
* we were loaded at aligned to a 2M boundary. %rbp contains the
@@ -295,6 +300,8 @@
.quad 0x /* NULL descriptor */
.quad 0x00af9a00 /* __KERNEL_CS */
.quad 0x00cf9200 /* __KERNEL_DS */
+ .quad 0x00808900 /* TS descriptor */
+ .quad 0x /* TS continued */
gdt_end:
.bss
/* Stack for uncompression */
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Gabriel Barazer wrote: Hi, After upgrading kernel to 2.6.22 on a Vmware workstation guest version 5.5 and 6 , the kernel decompression stage (Decompressing Linux...) is hanging for a very long time (~5 minutes) before finally succeeding (displaying done.\nBooting the kernel.\n). During this time, the VM process is eating all the CPU time during the decompression, like an infinite loop. Between these 2 strings is the gunzip() function at boot/compressed/misc.c which does the real job, and the problem seemed to appear since commit 1ab60e0f72f71ec54831e525a3e1154f1c092408. (2.6.22-rc1 hangs, 2.6.21.6 works). The problem occurs with or without CONFIG_RELOCATABLE enabled. What are the possible solutions to confirm where the problem is coming from ? Since I was just involved in the boot decompressor for another bug, I took a look at this. 2.6.22 switches it to be 64-bit code. VT is very picky about what state it can run in. Not using VT on Intel 64-bit hardware cripples performance, running at far below normal speed, and taking minutes to decompress the kernel, which is nearly instantaneous otherwise. To get back into VT in this case, not only do we need to load FS and GS, we also need to setup an initial LDT and task. Can you try the attached patch and see that it does the right thing? I've also cc'd the KVM developers, as the same problem will affect them, and hopefully the same patch will fix it. Thanks, Zach Zach VT is very picky about when it can enter execution. Get all segments setup and get LDT and TR into valid state to allow VT execution under VMware and KVM (untested). This makes the boot decompression run under VT, which makes it several orders of magnitude faster on 64-bit Intel hardware. Before, I was seeing times up to a minute or more to decompress a 1.3MB kernel on a very fast box. Signed-off-by: Zachary Amsden [EMAIL PROTECTED] === --- a/arch/x86_64/boot/compressed/head.S +++ a/arch/x86_64/boot/compressed/head.S @@ -195,6 +195,11 @@ movl %eax, %ds movl %eax, %es movl %eax, %ss + movl %eax, %fs + movl %eax, %gs + lldt %ax + movl$0x20, %eax + ltr %ax /* Compute the decompressed kernel start address. It is where * we were loaded at aligned to a 2M boundary. %rbp contains the @@ -295,6 +300,8 @@ .quad 0x /* NULL descriptor */ .quad 0x00af9a00 /* __KERNEL_CS */ .quad 0x00cf9200 /* __KERNEL_DS */ + .quad 0x00808900 /* TS descriptor */ + .quad 0x /* TS continued */ gdt_end: .bss /* Stack for uncompression */
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
On 08/04/2007 6:23:00 PM +0200, Zachary Amsden [EMAIL PROTECTED] wrote: Gabriel Barazer wrote: Hi, After upgrading kernel to 2.6.22 on a Vmware workstation guest version 5.5 and 6 , the kernel decompression stage (Decompressing Linux...) is hanging for a very long time (~5 minutes) before finally succeeding (displaying done.\nBooting the kernel.\n). During this time, the VM process is eating all the CPU time during the decompression, like an infinite loop. Between these 2 strings is the gunzip() function at boot/compressed/misc.c which does the real job, and the problem seemed to appear since commit 1ab60e0f72f71ec54831e525a3e1154f1c092408. (2.6.22-rc1 hangs, 2.6.21.6 works). The problem occurs with or without CONFIG_RELOCATABLE enabled. What are the possible solutions to confirm where the problem is coming from ? Since I was just involved in the boot decompressor for another bug, I took a look at this. 2.6.22 switches it to be 64-bit code. VT is very picky about what state it can run in. Not using VT on Intel 64-bit hardware cripples performance, running at far below normal speed, and taking minutes to decompress the kernel, which is nearly instantaneous otherwise. To get back into VT in this case, not only do we need to load FS and GS, we also need to setup an initial LDT and task. Can you try the attached patch and see that it does the right thing? It Works (tm) ! Tried compiling with and without the patch, with exactly the same config, just to be sure. Decompressing the kernel is now lightning fast. Thanks ! I've also cc'd the KVM developers, as the same problem will affect them, and hopefully the same patch will fix it. VT is very picky about when it can enter execution. Get all segments setup and get LDT and TR into valid state to allow VT execution under VMware and KVM (untested). This makes the boot decompression run under VT, which makes it several orders of magnitude faster on 64-bit Intel hardware. Before, I was seeing times up to a minute or more to decompress a 1.3MB kernel on a very fast box. Signed-off-by: Zachary Amsden [EMAIL PROTECTED] === --- a/arch/x86_64/boot/compressed/head.S +++ a/arch/x86_64/boot/compressed/head.S @@ -195,6 +195,11 @@ movl %eax, %ds movl %eax, %es movl %eax, %ss + movl %eax, %fs + movl %eax, %gs + lldt %ax + movl$0x20, %eax + ltr %ax /* Compute the decompressed kernel start address. It is where * we were loaded at aligned to a 2M boundary. %rbp contains the @@ -295,6 +300,8 @@ .quad 0x /* NULL descriptor */ .quad 0x00af9a00 /* __KERNEL_CS */ .quad 0x00cf9200 /* __KERNEL_DS */ + .quad 0x00808900 /* TS descriptor */ + .quad 0x /* TS continued */ gdt_end: .bss /* Stack for uncompression */
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Gabriel Barazer wrote:
Hi,
After upgrading kernel to 2.6.22 on a Vmware workstation guest version
5.5 and 6 , the kernel decompression stage ("Decompressing Linux...")
is hanging for a very long time (~5 minutes) before finally
succeeding (displaying "done.\nBooting the kernel.\n"). During this
time, the VM process is eating all the CPU time during the
decompression, like an infinite loop.
LKML is not the right place for this question. You are running on Intel
hardware?
Bring the discussion over to http://www.vmware.com/community forums
Zach
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Gabriel Barazer wrote: Hi, After upgrading kernel to 2.6.22 on a Vmware workstation guest version 5.5 and 6 , the kernel decompression stage (Decompressing Linux...) is hanging for a very long time (~5 minutes) before finally succeeding (displaying done.\nBooting the kernel.\n). During this time, the VM process is eating all the CPU time during the decompression, like an infinite loop. LKML is not the right place for this question. You are running on Intel hardware? Bring the discussion over to http://www.vmware.com/community forums Zach - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
