Re: [PATCH] tools/xg: increase LZMA_BLOCK_SIZE for uncompressing the kernel

["Anthony PERARD" <anthony.perard@xxxxxxxxxx>]

On Wed, Dec 18, 2024 at 06:58:25PM +0100, Roger Pau Monné wrote:
> On Tue, Oct 08, 2024 at 11:32:23PM +0200, Marek Marczykowski-Górecki wrote:
> > Linux 6.12-rc2 fails to decompress with the current 128MiB, contrary to
> > the code comment. It results in a failure like this:
> >
> >     domainbuilder: detail: xc_dom_kernel_file: 
> > filename="/var/lib/qubes/vm-kernels/6.12-rc2-1.1.fc37/vmlinuz"
> >     domainbuilder: detail: xc_dom_malloc_filemap    : 12104 kB
> >     domainbuilder: detail: xc_dom_module_file: 
> > filename="/var/lib/qubes/vm-kernels/6.12-rc2-1.1.fc37/initramfs"
> >     domainbuilder: detail: xc_dom_malloc_filemap    : 7711 kB
> >     domainbuilder: detail: xc_dom_boot_xen_init: ver 4.19, caps 
> > xen-3.0-x86_64 hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
> >     domainbuilder: detail: xc_dom_parse_image: called
> >     domainbuilder: detail: xc_dom_find_loader: trying multiboot-binary 
> > loader ...
> >     domainbuilder: detail: loader probe failed
> >     domainbuilder: detail: xc_dom_find_loader: trying HVM-generic loader ...
> >     domainbuilder: detail: loader probe failed
> >     domainbuilder: detail: xc_dom_find_loader: trying Linux bzImage loader 
> > ...
> >     domainbuilder: detail: _xc_try_lzma_decode: XZ decompression error: 
> > Memory usage limit reached
> >     xc: error: panic: xg_dom_bzimageloader.c:761: 
> > xc_dom_probe_bzimage_kernel unable to XZ decompress kernel: Invalid kernel
> >     domainbuilder: detail: loader probe failed
> >     domainbuilder: detail: xc_dom_find_loader: trying ELF-generic loader ...
> >     domainbuilder: detail: loader probe failed
> >     xc: error: panic: xg_dom_core.c:689: xc_dom_find_loader: no loader 
> > found: Invalid kernel
> >     libxl: error: libxl_dom.c:566:libxl__build_dom: xc_dom_parse_image 
> > failed
> >
> > The important part: XZ decompression error: Memory usage limit reached
> >
> > This looks to be related to the following change in Linux:
> > 8653c909922743bceb4800e5cc26087208c9e0e6 ("xz: use 128 MiB dictionary and 
> > force single-threaded mode")
> >
> > Fix this by increasing the block size to 256MiB. And remove the
> > misleading comment (from lack of better ideas).
> >
> > Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
>
> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>
> I assumed I already RB this, but it seems not.
>
> Could we get an Ack from the tools or libs maintainer for this to go
> in?  It's not the best solution, but we need to get this sorted in
> time for 4.20, and backport to stable branches.

Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,

--

 | Vates

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech